Flip game

String

65.0% acceptance

Mar 31, 2026

232

477

You are playing a Flip Game with your friend. You are given a string currentState that contains only '+' 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. Return all possible states of the string currentState after one valid move. You may return the answer in any order. If there is no valid move, return an empty list [].

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn generate_possible_next_moves(current_state: String) -> Vec<String> {
    let bytes = current_state.as_bytes();
    let mut result = Vec::new();
    for i in 0..bytes.len().saturating_sub(1) {
      if bytes[i] == b'+' && bytes[i + 1] == b'+' {
        let mut s = current_state.clone().into_bytes();
        s[i] = b'-';
        s[i + 1] = b'-';
        result.push(unsafe { String::from_utf8_unchecked(s) });
      }
    }
    result
  }
}