LeetCode 293. Flip Game

Problem Description:

You are playing the following Flip Game with your friend: Given a string that contains only these two characters: + and -, you and your friend take turns to flip two consecutive “++” into “–”. The game ends when a person can no longer make a move and therefore the other person will be the winner.

Write a function to compute all possible states of the string after one valid move.

For example, given s = “++++”, after one move, it may become one of the following states:
[
“–++”,
“+–+”,
“++–”
]
If there is no valid move, return an empty list [].

class Solution {public:    vector<string> generatePossibleNextMoves(string s) {    vector<string> res;    for(int i=0;i<s.size()-1;i++){        if(s.substr(i,2)=="++"){            s.substr(i,2)="--";            res.push_back(cur);            s.substr(i,2)="++";        }    }    return res;}