Submission #39378

#	Time	Username	Problem	Language	Result	Execution time	Memory
39378		aome	Sailing Race (CEOI12_race)	C++14	80 / 100	3000 ms	7156 KiB

race

#include <bits/stdc++.h>
using namespace std;

const int N = 505;
const int INF = 1e9;

int n, subtask;
int res, start;
int a[N][N];
int f[2][N][N];
int g[2][N][N];
int best[N];

int nxt(int i) { return i == (n - 1) ? 0 : (i + 1); }
int prv(int i) { return i == 0 ? (n - 1) : (i - 1); }

int calF(int t, int l, int r) {
    int &F = f[t][l][r];
    if (F != -1) return F;
    F = 0;
    if (t == 0) {
        for (int i = l; i != r; i = nxt(i)) {
            if (!a[l][i]) continue;
            F = max(F, max(calF(1, l, i), calF(0, i, r)) + 1);
        }
        if (res < F) res = F, start = l;
    }
    else {
        for (int i = nxt(l); i != r; i = nxt(i)) {
            if (!a[r][i]) continue;
            F = max(F, max(calF(0, i, r), calF(1, l, i)) + 1);
        }
        if (res < F) res = F, start = r;
    }
    return F;
}

int calG(int t, int l, int r) {
    int &G = g[t][l][r];
    if (G != -1) return G;
    if (l == r) return G = 0;
    G = -INF;
    if (t == 0) {
        for (int i = l; i != nxt(r); i = nxt(i)) {
            if (!a[l][i]) continue;
            G = max(G, calG(0, i, r) + 1);
        }
    }
    else {
        for (int i = l; i != r; i = nxt(i)) {
            if (!a[r][i]) continue;
            G = max(G, calG(1, l, i) + 1);
        }
    }
    return G;   
}

void updRes(int x, int y) {
    if (res < x) res = x, start = y;
}

int main() {
    ios::sync_with_stdio(false);
    cin >> n >> subtask;
    for (int i = 0; i < n; ++i) {
        int x; 
        while (cin >> x && x) a[i][x - 1] = 1;
    }
    memset(f, -1, sizeof f);
    memset(g, -1, sizeof g);
    for (int i = 0; i < 2; ++i) {
        for (int j = 0; j < n; ++j) {
            for (int k = 0; k < n; ++k) {
                calF(i, j, k), calG(i, j, k);
            }
        }
    }
    if (subtask == 0) {
        cout << res << '\n' << start + 1; return 0;
    }
    // fix S
    for (int S = 0; S < n; ++S) {
        memset(best, 0, sizeof best);
        for (int T = nxt(S); T != S; T = nxt(T)) {
            if (a[S][T]) {
                for (int i = T; i != S; i = nxt(i)) {
                    updRes(calG(0, T, i) + best[i] + 1, S);
                }
            }
            for (int i = T; i != S; i = nxt(i)) {
                if (!a[i][T]) continue;
                best[i] = max(best[i], calF(1, S, T) + 1);
            }
        }
    }
    for (int S = 0; S < n; ++S) {
        memset(best, 0, sizeof best);
        for (int T = prv(S); T != S; T = prv(T)) {
            if (a[S][T]) {
                for (int i = T; i != S; i = prv(i)) {
                    updRes(calG(1, i, T) + best[i] + 1, S);
                }
            }
            for (int i = T; i != S; i = prv(i)) {
                if (!a[i][T]) continue;
                best[i] = max(best[i], calF(0, T, S) + 1);
            }   
        }
    }
    // fix T
    for (int T = 0; T < n; ++T) {
        memset(best, 0, sizeof best);
        for (int S = nxt(T); S != T; S = nxt(S)) {
            if (a[S][T]) {
                for (int i = S; i != T; i = nxt(i)) {
                    updRes(calG(1, i, T) + best[i] + 1, S);
                }
            }
            for (int i = S; i != T; i = nxt(i)) {
                if (!a[i][S]) continue;
                best[i] = max(best[i], calF(1, T, S) + 1);
            }
        }
    }
    for (int T = 0; T < n; ++T) {
        memset(best, 0, sizeof best);
        for (int S = prv(T); S != T; S = prv(S)) {
            if (a[S][T]) {
                for (int i = S; i != T; i = prv(i)) {
                    updRes(calG(0, T, i) + best[i] + 1, S);
                }
            }
            for (int i = S; i != T; i = prv(i)) {
                if (!a[i][S]) continue;
                best[i] = max(best[i], calF(0, S, T) + 1);
            }
        }
    }
    cout << res << '\n' << start + 1;
}

• Subtask 1: 80 / 100