NEXT PERMUTATION .cpp

#include<bits/stdc++.h>
using namespace std;
class Solution
{
public:
     void nextPermutation(vector<int> &nums)
     {

          int ind = -1;
          int n = nums.size();

          // step 1 finding the breakpoint
          for (int i = n - 2; i >= 0; i--)
          {
               if (nums[i] < nums[i + 1])
               {
                    ind = i;
                    break;
               }
          }
          // if there is no break point then
          if (ind == -1)
          {
               reverse(nums.begin(), nums.end());
               return;
          }

          // Step 2 Now after we got the breakpoint from the back to that breakpoint we have to
          // find which is least greater
          for (int i = n - 1; i > ind; i--)
          {
               if (nums[i] > nums[ind])
               {
                    swap(nums[i], nums[ind]);
                    break;
               }
          }

          reverse(nums.begin() + ind + 1, nums.end());
     }
};

// LEETCODE PROBLEM - 31