293. Flip Game

293. Flip Game (Easy)

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.

Example:

Input: s = "++++"
Output: 
[
  "--++",
  "+--+",
  "++--"
]

Note: If there is no valid move, return an empty list [].

Companies:
Google

Related Topics:
String

Similar Questions:

• Flip Game II (Medium)

Solution 1.

// OJ: https://leetcode.com/problems/flip-game/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    vector<string> generatePossibleNextMoves(string s) {
        vector<string> ans;
        for (int i = 1, N = s.size(); i < N; ++i) {
            if (s[i] != '+' || s[i - 1] != '+') continue;
            ans.push_back(s);
            ans.back()[i] = ans.back()[i - 1] = '-';
        }
        return ans;
    }
};