Submission #55258

#	Time	Username	Problem	Language	Result	Execution time	Memory
55258		paulica	Sailing Race (CEOI12_race)	C++14	80 / 100	3083 ms	4964 KiB

race

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

#define _ << " _ " <<
#define TRACE(x) cout << #x << " = " << x << endl

const int MaxN = 510;
int n, m;
int sol, start;

bool con[MaxN][MaxN];

int memoA[MaxN][MaxN][2], memoB[MaxN][MaxN][2];

int nxt(int i, int d) {
    if (d == 1) return i == n - 1 ? 0 : i + 1;
    else return i == 0 ? n - 1 : i - 1;
}

int dpA(int i, int j, int d) {
    int& dp = memoA[i][j][d];
    if (dp != -1) return dp;
    
    if (i == j) dp = 1;
    else if (con[i][j]) dp = 2;
    else dp = 0;

    for (int k = i; k != j; k = nxt(k, d))
        if (con[k][j] && dpA(i, k, d) > 0) dp = max(dp, dpA(i, k, d) + 1);

    return dp;
}

int dpB(int i, int j, int d) {
    int& dp = memoB[i][j][d];
    if (dp != -1) return dp;

    dp = (i != j);

    for (int k = i; k != j; k = nxt(k, d))
        if (con[i][k]) {
            dp = max(dp, dpB(k, j, d) + 1);
            dp = max(dp, dpB(k, i, 1 - d) + 1);
        }

    return dp;
}

void check(int cnt, int s) {
    if (cnt > sol) {
        sol = cnt;
        start = s;
    }
}

void solveS(int x, int s, int d) {
    int maxB = 0, t = -1;

    for (int i = nxt(s, d); i != x; i = nxt(i, d)) {
        if (con[s][i]) {
            t = i;
            check(dpA(t, x, d) + maxB, s);
        }

        if (con[x][i])
            maxB = max(maxB, dpB(i, s, 1 - d));
    }
}

void solveT(int x, int t, int d) {
    int maxB = 0, s = -1;
    
    for (int i = nxt(x, d); i != t; i = nxt(i, d))
        if (con[i][t]) {
            s = i;
            break;
        }

    if (s == -1) return;

    for (int i = nxt(s, d); i != t; i = nxt(i, d))
        if (con[x][i])
            maxB = max(maxB, dpB(i, t, d));

    check(dpA(t, x, d) + maxB, s);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> m;

    for (int i = 0; i < n; i++) {
        int j;
        for (cin >> j; j != 0; cin >> j)
            con[i][j - 1] = true;

        for (int j = 0; j < n; j++)
            for (int d : {0, 1})
                memoA[i][j][d] = memoB[i][j][d] = -1;
    }

    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            for (int d : {0, 1})
                if (con[i][j]) check(dpB(j, i, d), i);

    if (m == 1)
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++)
                if (i != j) {
                    solveS(i, j, 0);
                    solveS(i, j, 1);
                    solveT(i, j, 0);
                    solveT(i, j, 1);
                }

    cout << sol << "\n" << start + 1 << "\n";

    return 0;
}

• Subtask 1: 80 / 100