C++ Programming Code Examples C++ > Sorting Searching Code Examples C++ Program to Find the Number of Permutations of a Given String C++ Program to Find the Number of Permutations of a Given String - This algorithm prints a total number of permutation possible for a given string. - The time complexity of this algorithm is O(n). - This algorithm takes the input of the string. - Then it checks for the repetition of the characters. - Compute the permutation and print the result. - Exit. #include<iostream> #include<string.h> using namespace std; // A function to find the factorial. int factorial(int n) { int i; for(i = n-1; i > 1; i--) n *= i; return n; } // A function to calculate the total number of permutation possible for the given set. int CountPermutation(char *str) { int countoccur[26] = {0}, len, i, res; len = strlen(str); // Count the occurrence of each character. for(i = 0; i < len; i++) { countoccur[str[i]-'a']++; } res = factorial(len); // Divide the length factorial by the factorial of number of occurrence of each character. for(i = 0; i < 26; i++) { if(countoccur[i] > 1) res = res/factorial(countoccur[i]); } return res; } int main() { int result; char str[100]; cout<<"A program to find a permutation of a given string: "; cout<<"\n\n\tEnter the string: "; cin>>str; // Get result using CountPermutation(). result = CountPermutaion(str); cout<<"\nThe number of possible permutation are: "<<result; return 0; }
