Submission #669490

#	Time	Username	Problem	Language	Result	Execution time	Memory
669490		GrandTiger1729	Collecting Stamps 3 (JOI20_ho_t3)	C++17	100 / 100	162 ms	126148 KiB

ho_t3

#include <iostream>
using namespace std;

const long long INF = 1e18;
int main(){
    int n;
    long long L;
    cin >> n >> L;
    long long a[n], b[n];
    for (int i = 0; i < n; i++){
        cin >> a[i];
    }
    for (int i = 0; i < n; i++){
        cin >> b[i];
    }
    auto idx = [&](int i) -> int {
        return (i % n + n) % n;
    };
    auto dis = [&](long long x, long long y) -> long long {
        if (x > y) swap(x, y);
        return min(y - x, x + L - y);
    };
    long long dp[n][n][n + 1][2]{}; // [l, r], pickcnt, cur(l, r) => min time
    fill_n(&dp[0][0][0][0], sizeof(dp) / sizeof(long long), INF);
    for (int i = 0; i < n; i++){
        dp[i][i][min(a[i], L - a[i]) <= b[i]][0] = dp[i][i][min(a[i], L - a[i]) <= b[i]][1] = min(a[i], L - a[i]);
    }
    for (int t = 0; t < n - 1; t++){
        for (int l = n - 1; l >= 0; l--){
            int r = idx(l + t);
            for (int i = 0; i < n; i++){
                if (dp[l][r][i][0] + dis(a[l], a[idx(l - 1)]) <= b[idx(l - 1)])
                    dp[idx(l - 1)][r][i + 1][0] = min(dp[idx(l - 1)][r][i + 1][0], dp[l][r][i][0] + dis(a[l], a[idx(l - 1)]));
                if (dp[l][r][i][1] + dis(a[r], a[idx(l - 1)]) <= b[idx(l - 1)])
                    dp[idx(l - 1)][r][i + 1][0] = min(dp[idx(l - 1)][r][i + 1][0], dp[l][r][i][1] + dis(a[r], a[idx(l - 1)]));
                if (dp[l][r][i][0] + dis(a[l], a[idx(r + 1)]) <= b[idx(r + 1)])
                    dp[l][idx(r + 1)][i + 1][1] = min(dp[l][idx(r + 1)][i + 1][1], dp[l][r][i][0] + dis(a[l], a[idx(r + 1)]));
                if (dp[l][r][i][1] + dis(a[r], a[idx(r + 1)]) <= b[idx(r + 1)])
                    dp[l][idx(r + 1)][i + 1][1] = min(dp[l][idx(r + 1)][i + 1][1], dp[l][r][i][1] + dis(a[r], a[idx(r + 1)]));
            }
            for (int i = 0; i <= n; i++){
                dp[idx(l - 1)][r][i][0] = min(dp[idx(l - 1)][r][i][0], dp[l][r][i][0] + dis(a[l], a[idx(l - 1)]));
                dp[idx(l - 1)][r][i][0] = min(dp[idx(l - 1)][r][i][0], dp[l][r][i][1] + dis(a[r], a[idx(l - 1)]));
                dp[l][idx(r + 1)][i][1] = min(dp[l][idx(r + 1)][i][1], dp[l][r][i][0] + dis(a[l], a[idx(r + 1)]));
                dp[l][idx(r + 1)][i][1] = min(dp[l][idx(r + 1)][i][1], dp[l][r][i][1] + dis(a[r], a[idx(r + 1)]));
            }
        }
    }
    for (int i = n; i >= 0; i--){
        for (int j = 0; j < n; j++){
            if (dp[j][idx(j + n - 1)][i][0] != INF || dp[j][idx(j + n - 1)][i][1] != INF){
                cout << i;
                return 0;
            }
        }
    }
    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 75 / 75