LeetCode 五月打卡-day22

Posted 2022-05-23 王六六的IT日常

464. 我能赢吗

参考题解：
【负雪明烛】图解算法：递归，步步优化，弄清每个细节
【宫水三叶】博弈论 DP 运用题

class Solution 
    int n, t;
    int[][] f = new int[1 << 20][2];
    // 1 true / -1 false
    int dfs(int state, int tot, int k) 
        if (state == ((1 << n) - 1) && tot < t) return -1;
        if (f[state][k % 2] != 0) return f[state][k % 2];
        int hope = k % 2 == 0 ? 1 : -1;
        for (int i = 0; i < n; i++) 
            if (((state >> i) & 1) == 1) continue;
            if (tot + i + 1 >= t) return f[state][k % 2] = hope;
            if (dfs(state | (1 << i), tot + i + 1, k + 1) == hope) return f[state][k % 2] = hope;
        
        return f[state][k % 2] = -hope;
    
    public boolean canIWin(int _n, int _t) 
        n = _n; t = _t;
        if (t == 0) return true;
        return dfs(0, 0, 0) == 1;