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Egy adott tartományban lévő szám osztóinak maximális számának lekérdezése

Adott típusú Q lekérdezések: L R minden lekérdezéshez ki kell nyomtatnia a számhoz tartozó osztók maximális számát x (L<= x <= R) rendelkezik. 
Példák:  
 

  L = 1 R = 10  : 1 has 1 divisor. 2 has 2 divisors. 3 has 2 divisors. 4 has 3 divisors. 5 has 2 divisors. 6 has 4 divisors. 7 has 2 divisors. 8 has 4 divisors. 9 has 3 divisors. 10 has 4 divisors. So the answer for above query is 4 as it is the maximum number of divisors a number has in [1 10].


 


Előfeltételek: Eratosthenes szita Szegmens fa
Az alábbiakban a probléma megoldásának lépései találhatók.
 



  1. Először is nézzük meg, hány osztó van egy számban n = p1k1* p2k2* ... * pnkn (ahol p1p2... pnprímszámok) rendelkezik; a válasz az (k1+ 1)*(k2+ 1)*...*(kn+ 1) . Hogyan? Minden prímtényezős prímszámhoz megkaphatjuk a sajátját kén+ 1 lehetséges hatványok egy osztóban (0 1 2... kén).
  2. Most nézzük meg, hogyan találhatjuk meg egy szám prímtényezősségét, és először építünk egy tömböt legkisebb_prím[] amely a legkisebb prímosztóját tárolja én at énth index elosztunk egy számot a legkisebb prímosztójával, hogy új számot kapjunk (ennek az új számnak a legkisebb prímosztóját is tároljuk) addig csináljuk, amíg a szám legkisebb prímje meg nem változik, amikor az új szám legkisebb prímtényezője eltér az előző számtól.énaz ithprímszám az adott szám prímtényezősségében.
  3. Végül megkapjuk az összes szám osztóinak számát, és eltároljuk azokat egy szegmensfában, amely megtartja a szegmensek maximális számát. Minden lekérdezésre a szegmensfa lekérdezésével válaszolunk.


 

C++
// A C++ implementation of the above idea to process // queries of finding a number with maximum divisors. #include    using namespace std; #define maxn 1000005 #define INF 99999999 int smallest_prime[maxn]; int divisors[maxn]; int segmentTree[4 * maxn]; // Finds smallest prime factor of all numbers in // range[1 maxn) and stores them in smallest_prime[] // smallest_prime[i] should contain the smallest prime // that divides i void findSmallestPrimeFactors() {  // Initialize the smallest_prime factors of all  // to infinity  for (int i = 0 ; i < maxn ; i ++ )  smallest_prime[i] = INF;  // to be built like eratosthenes sieve  for (long long i = 2; i < maxn; i++)  {  if (smallest_prime[i] == INF)  {  // prime number will have its smallest_prime  // equal to itself  smallest_prime[i] = i;  for (long long j = i * i; j < maxn; j += i)  // if 'i' is the first prime number reaching 'j'  if (smallest_prime[j] > i)  smallest_prime[j] = i;  }  } } // number of divisors of n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn) // are equal to (k1+1) * (k2+1) ... (kn+1) // this function finds the number of divisors of all numbers // in range [1 maxn) and stores it in divisors[] // divisors[i] stores the number of divisors i has void buildDivisorsArray() {  for (int i = 1; i < maxn; i++)  {  divisors[i] = 1;  int n = i p = smallest_prime[i] k = 0;  // we can obtain the prime factorization of the number n  // n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn) using the  // smallest_prime[] array we keep dividing n by its  // smallest_prime until it becomes 1 whilst we check  // if we have need to set k zero  while (n > 1)  {  n = n / p;  k ++;  if (smallest_prime[n] != p)  {  //use p^k initialize k to 0  divisors[i] = divisors[i] * (k + 1);  k = 0;  }  p = smallest_prime[n];  }  } } // builds segment tree for divisors[] array void buildSegtmentTree(int node int a int b) {  // leaf node  if (a == b)  {  segmentTree[node] = divisors[a];  return ;  }  //build left and right subtree  buildSegtmentTree(2 * node a (a + b) / 2);  buildSegtmentTree(2 * node + 1 ((a + b) / 2) + 1 b);  //combine the information from left  //and right subtree at current node  segmentTree[node] = max(segmentTree[2 * node]  segmentTree[2 *node + 1]); } //returns the maximum number of divisors in [l r] int query(int node int a int b int l int r) {  // If current node's range is disjoint with query range  if (l > b || a > r)  return -1;  // If the current node stores information for the range  // that is completely inside the query range  if (a >= l && b <= r)  return segmentTree[node];  // Returns maximum number of divisors from left  // or right subtree  return max(query(2 * node a (a + b) / 2 l r)  query(2 * node + 1 ((a + b) / 2) + 1 blr)); } // driver code int main() {  // First find smallest prime divisors for all  // the numbers  findSmallestPrimeFactors();  // Then build the divisors[] array to store  // the number of divisors  buildDivisorsArray();  // Build segment tree for the divisors[] array  buildSegtmentTree(1 1 maxn - 1);  cout << 'Maximum divisors that a number has '  << ' in [1 100] are '  << query(1 1 maxn - 1 1 100) << endl;  cout << 'Maximum divisors that a number has'  << ' in [10 48] are '  << query(1 1 maxn - 1 10 48) << endl;  cout << 'Maximum divisors that a number has'  << ' in [1 10] are '  << query(1 1 maxn - 1 1 10) << endl;  return 0; } 
Java
// Java implementation of the above idea to process // queries of finding a number with maximum divisors. import java.util.*; class GFG { static int maxn = 10005; static int INF = 999999; static int []smallest_prime = new int[maxn]; static int []divisors = new int[maxn]; static int []segmentTree = new int[4 * maxn]; // Finds smallest prime factor of all numbers  // in range[1 maxn) and stores them in  // smallest_prime[] smallest_prime[i] should  // contain the smallest prime that divides i static void findSmallestPrimeFactors() {  // Initialize the smallest_prime factors   // of all to infinity  for (int i = 0 ; i < maxn ; i ++ )  smallest_prime[i] = INF;  // to be built like eratosthenes sieve  for (int i = 2; i < maxn; i++)  {  if (smallest_prime[i] == INF)  {  // prime number will have its   // smallest_prime equal to itself  smallest_prime[i] = i;  for (int j = i * i; j < maxn; j += i)  // if 'i' is the first  // prime number reaching 'j'  if (smallest_prime[j] > i)  smallest_prime[j] = i;  }  } } // number of divisors of n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn) // are equal to (k1+1) * (k2+1) ... (kn+1) // this function finds the number of divisors of all numbers // in range [1 maxn) and stores it in divisors[] // divisors[i] stores the number of divisors i has static void buildDivisorsArray() {  for (int i = 1; i < maxn; i++)  {  divisors[i] = 1;  int n = i p = smallest_prime[i] k = 0;  // we can obtain the prime factorization of   // the number n n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn)   // using the smallest_prime[] array we keep dividing n   // by its smallest_prime until it becomes 1   // whilst we check if we have need to set k zero  while (n > 1)  {  n = n / p;  k ++;  if (smallest_prime[n] != p)  {  // use p^k initialize k to 0  divisors[i] = divisors[i] * (k + 1);  k = 0;  }  p = smallest_prime[n];  }  } } // builds segment tree for divisors[] array static void buildSegtmentTree(int node int a int b) {  // leaf node  if (a == b)  {  segmentTree[node] = divisors[a];  return ;  }  //build left and right subtree  buildSegtmentTree(2 * node a (a + b) / 2);  buildSegtmentTree(2 * node + 1 ((a + b) / 2) + 1 b);  //combine the information from left  //and right subtree at current node  segmentTree[node] = Math.max(segmentTree[2 * node]  segmentTree[2 *node + 1]); } // returns the maximum number of divisors in [l r] static int query(int node int a int b int l int r) {  // If current node's range is disjoint  // with query range  if (l > b || a > r)  return -1;  // If the current node stores information   // for the range that is completely inside  // the query range  if (a >= l && b <= r)  return segmentTree[node];  // Returns maximum number of divisors from left  // or right subtree  return Math.max(query(2 * node a (a + b) / 2 l r)  query(2 * node + 1   ((a + b) / 2) + 1 b l r)); } // Driver Code public static void main(String[] args)  {    // First find smallest prime divisors   // for all the numbers  findSmallestPrimeFactors();  // Then build the divisors[] array to store  // the number of divisors  buildDivisorsArray();  // Build segment tree for the divisors[] array  buildSegtmentTree(1 1 maxn - 1);  System.out.println('Maximum divisors that a number ' +   'has in [1 100] are ' +   query(1 1 maxn - 1 1 100));  System.out.println('Maximum divisors that a number ' +   'has in [10 48] are ' +   query(1 1 maxn - 1 10 48));  System.out.println('Maximum divisors that a number ' +   'has in [1 10] are ' +   query(1 1 maxn - 1 1 10));  } } // This code is contributed by PrinciRaj1992 
Python 3
# Python 3 implementation of the above  # idea to process queries of finding a # number with maximum divisors. maxn = 1000005 INF = 99999999 smallest_prime = [0] * maxn divisors = [0] * maxn segmentTree = [0] * (4 * maxn) # Finds smallest prime factor of all  # numbers in range[1 maxn) and stores  # them in smallest_prime[] smallest_prime[i]  # should contain the smallest prime that divides i def findSmallestPrimeFactors(): # Initialize the smallest_prime  # factors of all to infinity for i in range(maxn ): smallest_prime[i] = INF # to be built like eratosthenes sieve for i in range(2 maxn): if (smallest_prime[i] == INF): # prime number will have its  # smallest_prime equal to itself smallest_prime[i] = i for j in range(i * i maxn  i): # if 'i' is the first prime # number reaching 'j' if (smallest_prime[j] > i): smallest_prime[j] = i # number of divisors of n = (p1 ^ k1) *  # (p2 ^ k2) ... (pn ^ kn) are equal to  # (k1+1) * (k2+1) ... (kn+1). This function # finds the number of divisors of all numbers # in range [1 maxn) and stores it in divisors[] # divisors[i] stores the number of divisors i has def buildDivisorsArray(): for i in range(1 maxn): divisors[i] = 1 n = i p = smallest_prime[i] k = 0 # we can obtain the prime factorization  # of the number n n = (p1 ^ k1) * (p2 ^ k2)  # ... (pn ^ kn) using the smallest_prime[]  # array we keep dividing n by its  # smallest_prime until it becomes 1 whilst  # we check if we have need to set k zero while (n > 1): n = n // p k += 1 if (smallest_prime[n] != p): # use p^k initialize k to 0 divisors[i] = divisors[i] * (k + 1) k = 0 p = smallest_prime[n] # builds segment tree for divisors[] array def buildSegtmentTree( node a b): # leaf node if (a == b): segmentTree[node] = divisors[a] return #build left and right subtree buildSegtmentTree(2 * node a (a + b) // 2) buildSegtmentTree(2 * node + 1 ((a + b) // 2) + 1 b) #combine the information from left #and right subtree at current node segmentTree[node] = max(segmentTree[2 * node] segmentTree[2 * node + 1]) # returns the maximum number of  # divisors in [l r] def query(node a b l r): # If current node's range is disjoint # with query range if (l > b or a > r): return -1 # If the current node stores information  # for the range that is completely inside  # the query range if (a >= l and b <= r): return segmentTree[node] # Returns maximum number of divisors  # from left or right subtree return max(query(2 * node a (a + b) // 2 l r) query(2 * node + 1 ((a + b) // 2) + 1 b l r)) # Driver code if __name__ == '__main__': # First find smallest prime divisors  # for all the numbers findSmallestPrimeFactors() # Then build the divisors[] array to  # store the number of divisors buildDivisorsArray() # Build segment tree for the divisors[] array buildSegtmentTree(1 1 maxn - 1) print('Maximum divisors that a number has ' ' in [1 100] are ' query(1 1 maxn - 1 1 100)) print('Maximum divisors that a number has' ' in [10 48] are ' query(1 1 maxn - 1 10 48)) print( 'Maximum divisors that a number has' ' in [1 10] are ' query(1 1 maxn - 1 1 10)) # This code is contributed by ita_c 
C#
// C# implementation of the above idea  // to process queries of finding a number // with maximum divisors. using System;   class GFG { static int maxn = 10005; static int INF = 999999; static int []smallest_prime = new int[maxn]; static int []divisors = new int[maxn]; static int []segmentTree = new int[4 * maxn]; // Finds smallest prime factor of all numbers  // in range[1 maxn) and stores them in  // smallest_prime[] smallest_prime[i] should  // contain the smallest prime that divides i static void findSmallestPrimeFactors() {  // Initialize the smallest_prime   // factors of all to infinity  for (int i = 0 ; i < maxn ; i ++ )  smallest_prime[i] = INF;  // to be built like eratosthenes sieve  for (int i = 2; i < maxn; i++)  {  if (smallest_prime[i] == INF)  {  // prime number will have its   // smallest_prime equal to itself  smallest_prime[i] = i;  for (int j = i * i; j < maxn; j += i)  // if 'i' is the first  // prime number reaching 'j'  if (smallest_prime[j] > i)  smallest_prime[j] = i;  }  } } // number of divisors of  // n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn) // are equal to (k1+1) * (k2+1) ... (kn+1) // this function finds the number of divisors  // of all numbers in range [1 maxn) and stores  // it in divisors[] divisors[i] stores the // number of divisors i has static void buildDivisorsArray() {  for (int i = 1; i < maxn; i++)  {  divisors[i] = 1;  int n = i p = smallest_prime[i] k = 0;  // we can obtain the prime factorization of   // the number n   // n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn)   // using the smallest_prime[] array   // we keep dividing n by its smallest_prime   // until it becomes 1 whilst we check if  // we have need to set k zero  while (n > 1)  {  n = n / p;  k ++;  if (smallest_prime[n] != p)  {  // use p^k initialize k to 0  divisors[i] = divisors[i] * (k + 1);  k = 0;  }  p = smallest_prime[n];  }  } } // builds segment tree for divisors[] array static void buildSegtmentTree(int node   int a int b) {  // leaf node  if (a == b)  {  segmentTree[node] = divisors[a];  return;  }  //build left and right subtree  buildSegtmentTree(2 * node a (a + b) / 2);  buildSegtmentTree(2 * node + 1   ((a + b) / 2) + 1 b);  //combine the information from left  //and right subtree at current node  segmentTree[node] = Math.Max(segmentTree[2 * node]  segmentTree[2 *node + 1]); } // returns the maximum number of divisors in [l r] static int query(int node int a int b int l int r) {  // If current node's range is disjoint  // with query range  if (l > b || a > r)  return -1;  // If the current node stores information   // for the range that is completely inside  // the query range  if (a >= l && b <= r)  return segmentTree[node];  // Returns maximum number of divisors from left  // or right subtree  return Math.Max(query(2 * node a (a + b) / 2 l r)  query(2 * node + 1   ((a + b) / 2) + 1 b l r)); } // Driver Code public static void Main(String[] args)  {    // First find smallest prime divisors   // for all the numbers  findSmallestPrimeFactors();  // Then build the divisors[] array   // to store the number of divisors  buildDivisorsArray();  // Build segment tree for the divisors[] array  buildSegtmentTree(1 1 maxn - 1);  Console.WriteLine('Maximum divisors that a number ' +   'has in [1 100] are ' +   query(1 1 maxn - 1 1 100));  Console.WriteLine('Maximum divisors that a number ' +   'has in [10 48] are ' +   query(1 1 maxn - 1 10 48));  Console.WriteLine('Maximum divisors that a number ' +   'has in [1 10] are ' +   query(1 1 maxn - 1 1 10));  } } // This code is contributed by 29AjayKumar 
JavaScript
<script> // JavaScript implementation of the above idea to process // queries of finding a number with maximum divisors.    let maxn = 10005;  let INF = 999999;  let smallest_prime = new Array(maxn);  for(let i=0;i<maxn;i++)  {  smallest_prime[i]=0;  }  let divisors = new Array(maxn);  for(let i=0;i<maxn;i++)  {  divisors[i]=0;  }  let segmentTree = new Array(4 * maxn);  for(let i=0;i<4*maxn;i++)  {  segmentTree[i]=0;  }    // Finds smallest prime factor of all numbers   // in range[1 maxn) and stores them in   // smallest_prime[] smallest_prime[i] should   // contain the smallest prime that divides i  function findSmallestPrimeFactors()  {  // Initialize the smallest_prime factors   // of all to infinity  for (let i = 0 ; i < maxn ; i ++ )  smallest_prime[i] = INF;    // to be built like eratosthenes sieve  for (let i = 2; i < maxn; i++)  {  if (smallest_prime[i] == INF)  {  // prime number will have its   // smallest_prime equal to itself  smallest_prime[i] = i;  for (let j = i * i; j < maxn; j += i)  {   // if 'i' is the first  // prime number reaching 'j'  if (smallest_prime[j] > i)  smallest_prime[j] = i;  }  }  }  }    // number of divisors of n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn)  // are equal to (k1+1) * (k2+1) ... (kn+1)  // this function finds the number of divisors of all numbers  // in range [1 maxn) and stores it in divisors[]  // divisors[i] stores the number of divisors i has  function buildDivisorsArray()  {  for (let i = 1; i < maxn; i++)  {  divisors[i] = 1;  let n = i;  let p = smallest_prime[i]  let k = 0;    // we can obtain the prime factorization of   // the number n n = (p1 ^ k1) * (p2 ^ k2) ... (pn ^ kn)   // using the smallest_prime[] array we keep dividing n   // by its smallest_prime until it becomes 1   // whilst we check if we have need to set k zero  while (n > 1)  {  n = Math.floor(n / p);  k++;    if (smallest_prime[n] != p)  {  // use p^k initialize k to 0  divisors[i] = divisors[i] * (k + 1);  k = 0;  }  p = smallest_prime[n];  }  }  }    // builds segment tree for divisors[] array  function buildSegtmentTree(nodeab)  {  // leaf node  if (a == b)  {  segmentTree[node] = divisors[a];  return ;  }    //build left and right subtree  buildSegtmentTree(2 * node a Math.floor((a + b) / 2));  buildSegtmentTree((2 * node) + 1 Math.floor((a + b) / 2) + 1 b);    //combine the information from left  //and right subtree at current node  segmentTree[node] = Math.max(segmentTree[2 * node]  segmentTree[(2 *node) + 1]);  }    // returns the maximum number of divisors in [l r]  function query(nodeablr)  {  // If current node's range is disjoint  // with query range  if (l > b || a > r)  return -1;    // If the current node stores information   // for the range that is completely inside  // the query range  if (a >= l && b <= r)  return segmentTree[node];    // Returns maximum number of divisors from left  // or right subtree  return Math.max(query(2 * node a   Math.floor((a + b) / 2) l r)  query(2 * node + 1  Math.floor((a + b) / 2) + 1 b l r));  }  // Driver Code    // First find smallest prime divisors   // for all the numbers  findSmallestPrimeFactors();    // Then build the divisors[] array to store  // the number of divisors  buildDivisorsArray();    // Build segment tree for the divisors[] array  buildSegtmentTree(1 1 maxn - 1);    document.write('Maximum divisors that a number ' +  'has in [1 100] are ' + query(1 1 maxn - 1 1 100)+'  
'
); document.write('Maximum divisors that a number ' + 'has in [10 48] are ' + query(1 1 maxn - 1 10 48)+'
'
); document.write('Maximum divisors that a number ' + 'has in [1 10] are ' + query(1 1 maxn - 1 1 10)+'
'
); // This code is contributed by avanitrachhadiya2155 </script>

Kimenet:  
 

Maximum divisors that a number has in [1 100] are 12 Maximum divisors that a number has in [10 48] are 10 Maximum divisors that a number has in [1 10] are 4

Időbeli összetettség:  O((maxn + Q) * log(maxn))

  • Szitához: O(maxn * log(log(maxn)) )
  • Az egyes számok osztóinak kiszámításához: Rendben van1 + k2 + ... + kn) < O(log(maxn))
  • Az egyes tartományok lekérdezéséhez: O(log(maxn))

Kiegészítő tér: On)

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