Submission #771463

#	Time	Username	Problem	Language	Result	Execution time	Memory
771463		vjudge1	Snake Escaping (JOI18_snake_escaping)	C++17	22 / 100	949 ms	65536 KiB

snake_escaping

// #cheat_when_I_was_young
// #cheatkhitacontre #khionhatoicheat
// #thaycuckythatvong
#include "bits/stdc++.h"
using namespace std;
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
const int N = 1<<20, M = 21;
int n, q, dp[N][M], sup[N][M];
string s, t;
int backtrack1(int idx, int num) {
    if (idx == n) return s[num];
    if (t[idx] == '0') return backtrack1(idx+1, num);
    if (t[idx] == '1') return backtrack1(idx+1, num | (1<<idx));
    return backtrack1(idx+1, num) + backtrack1(idx+1, num | (1<<idx));
}
int backtrack2(int idx, int num, int change) {
    if (idx == n) {
        if (change % 2) return -dp[num][0];
        return dp[num][0];
    }
    if (t[idx] == '0') return backtrack2(idx+1, num, change);
    if (t[idx] == '?') return backtrack2(idx+1, num | (1<<idx), change);
    return backtrack2(idx+1, num, change+1) + backtrack2(idx+1, num | (1<<idx), change);
}
int backtrack3(int idx, int num, int change) {
    if (idx == n) {
        if (change % 2) return -sup[num][0];
        return sup[num][0];
    }
    if (t[idx] == '1') return backtrack3(idx+1, num | (1<<idx), change);
    if (t[idx] == '?') return backtrack3(idx+1, num, change);
    return backtrack3(idx+1, num, change) + backtrack3(idx+1, num | (1<<idx), change+1);
}
signed main() {
	IOS;
    cin >> n >> q >> s;
    for (int mask = 0; mask < 1<<n; ++mask) {
        s[mask] -= '0';
        dp[mask][n] = sup[mask][n] = s[mask];
    }
    for (int mask = 0; mask < 1<<n; ++mask) for (int i = n-1; i >= 0; --i) {
        dp[mask][i] = dp[mask][i+1];
        if (mask & (1<<i)) dp[mask][i] += dp[mask^(1<<i)][i+1];
    }
    for (int mask = (1<<n)-1; mask >= 0; --mask) for (int i = n-1; i >= 0; --i) {
        sup[mask][i] = sup[mask][i+1];
        if (!(mask & (1<<i))) sup[mask][i] += sup[mask^(1<<i)][i+1];
    }
    while (q--) {
        cin >> t;
        reverse(t.begin(), t.end());
        int cnt[] = {0, 0, 0};
        for (char &c: t) {
            if (c == '0') ++cnt[0];
            else if (c == '1') ++cnt[1];
            else ++cnt[2];
        }
        if (cnt[2] <= 6) cout << backtrack1(0, 0) << "\n";
        else if (cnt[1] <= 6) cout << backtrack2(0, 0, 0) << "\n";
        else cout << backtrack3(0, 0, 0) << "\n";
    }
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 10 / 10
• Subtask 4: 0 / 53
• Subtask 5: 0 / 25