31. Next Permutation.cpp

class Solution {
public:
    void nextPermutation(vector<int>& A) {
        int pivot = -1, n = A.size();

        for(int i=n-2; i>=0; i--){
            if(A[i] < A[i+1]){
                pivot = i;
                break;
            }
        }

        if(pivot == -1){
            reverse(A.begin(), A.end());
            return;
        }

        for(int i=n-1; i>pivot; i--){
            if(A[i] > A[pivot]){
                swap(A[i], A[pivot]);
                break;
            }
        }

        reverse(A.begin()+pivot+1, A.end());
    }
};