博弈论-leetcode-周赛261-5892. 石子游戏 IX

5892. 石子游戏 IX - 力扣（LeetCode） (leetcode-cn.com)

class Solution {
    public boolean stoneGameIX(int[] stones) {
        int n = stones.length;
        int[] cnt = new int[3];
        for (int i = 0; i < n; i++) {
            stones[i] %= 3;
            cnt[stones[i]]++;
        }
        if (canAliceWin(1, cnt) || canAliceWin(2, cnt)) return true;
        return false;
    }

    private boolean canAliceWin(int start, int[] cnt) {
        int[] cnt2 = new int[3];
        for (int i = 0; i < 3; i++) {
            cnt2[i] = cnt[i];
        }
        int turn, sum;
        if (cnt2[start] == 0) return false;
        cnt2[start]--;
        sum = start;
        turn = 1;
        while (true) {
            if (cnt2[0] > 0) {
                cnt2[0]--;
            } else if (cnt2[sum] > 0) {
                cnt2[sum]--;
                sum = (sum + sum) % 3;
            } else {
                break;
            }
            turn = 1 - turn;
        }
        if (cnt2[0] + cnt2[1] + cnt2[2] == 0) return false;
        return turn == 1;
    }

}