Print all distinct permutations of a given string with duplicates in C++


In this problem, we are given a string that may contain duplicate characters. Our task is to print all distinct permutations of the strings.

Let’s take an example to understand the problem −

Input: string = “XYZ”
Output: XYZ XZY YXZ YZX ZYX ZXY

To solve this problem, we have to fix one element of the string. And then iterate all the elements of the strings.

Example

Program to implement our solution,

 Live Demo

#include <string.h>
#include <iostream>
using namespace std;
int compare(const void* a, const void* b) {
   return (*(char*)a - *(char*)b);
}
void swapChar(char* a, char* b) {
   char t = *a;
   *a = *b;
   *b = t;
}
int findCeil(char str[], char first, int l, int h) {
   int ceilIndex = l;
   for (int i = l + 1; i <= h; i++)
      if (str[i] > first && str[i] < str[ceilIndex])
         ceilIndex = i;
   return ceilIndex;
}
void printPermutations(char str[]) {
   int size = strlen(str);
   qsort(str, size, sizeof(str[0]), compare);
   bool isFinished = false;
   while (!isFinished) {
      static int x = 1;
      cout<<str<<"\t";
      int i;
      for (i = size - 2; i >= 0; --i)
         if (str[i] < str[i + 1])
      break;
      if (i == -1)
         isFinished = true;
      else {
         int ceilIndex = findCeil(str,
         str[i], i + 1, size - 1);
         swapChar(&str[i], &str[ceilIndex]);
         qsort(str + i + 1, size - i - 1,
         sizeof(str[0]), compare);
      }
   }
}
int main() {
   char str[] = "SNGY";
   cout<<"All permutations of the string"<<str<<" are :\n";
   printPermutations(str);
   return 0;
}

Output

All permutations of the stringSNGY are −
GNSY GNYS GSNY GSYN GYNS GYSN NGSY NGYS NSGY NSYG NYGS NYSG SGNY SGYN SNGY SNYG SYGN SYNG YGNS YGSN YNGS YNSG YSGN YSNG

Updated on: 22-Jan-2020

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