Submission #328812

#	Time	Username	Problem	Language	Result	Execution time	Memory
328812		thecodingwizard	Sailing Race (CEOI12_race)	C++11	40 / 100	178 ms	9964 KiB

race

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define ii pair<int, int>
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define all(x) x.begin(), x.end()
#define F0R(i, n) for (int i = 0; i < n; i++)
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define inf 1000000010

#define maxn 500
int n, k; 
vector<int> adj[maxn];
vector<int> radj[maxn];

int memo[maxn][maxn][2];
int dp(int x, int y, bool onY) {
    if (memo[x][y][onY] != -1) return memo[x][y][onY];
    int best = 1;

    for (int i : adj[onY ? y : x]) {
        bool legal = false;
        if (x < y) {
            if (x < i && i < y) {
                legal = true;
            }
        } else {
            if (i > x || i < y) {
                legal = true;
            }
        }
        if (!legal) continue;

        best = max(best, 1 + max(dp(x, i, 1), dp(i, y, 0)));
    }

    return memo[x][y][onY] = best;
}

// path[i][x] = longest path to x starting from i, going counterclockwise
int path[maxn][maxn];
// going clockwise
int pathRev[maxn][maxn];

int main() {
    cin.tie(0)->sync_with_stdio(0);

    cin >> n >> k;
    F0R(i, n) {
        int x;
        while (cin >> x && x != 0) {
            --x;
            adj[i].pb(x);
            radj[x].pb(i);
        }
    }

    int best = -1, bestIdx = -1;

    F0R(i, n) F0R(j, n) F0R(k, 2) memo[i][j][k] = -1;

    F0R(i, n) {
        path[i][i] = pathRev[i][i] = 1;
    }

    F0R(i, n) {
        for (int j : adj[i]) {
            int val = max(dp(i, j, 1), dp(j, i, 0));
            if (best < val) {
                best = val;
                bestIdx = i;
            }
        }
        if (k) {
            sort(all(radj[i]), [&i](int x, int y){return (i-x+n)%n-(i-y+n)%n;});

            int add = 0;
            for (int j : radj[i]) {
                //while (add < n && ((i < j && (i+add)%n < j) || (i > j && ((i+add)%n > i || (i+add)%n < j)))) {
                while (add < (j-i+n)%n) {
                    int cur = (i+add)%n;
                    add++;
                    if (path[i][cur] == 0) continue;
                    for (int nxt : adj[cur]) {
                        if ((cur >= i && (nxt > cur || nxt < i)) || (cur <= i && (cur < nxt && nxt < i))) {
                            path[i][nxt] = max(path[i][nxt], path[i][cur]+1);
                        }
                    }
                }
                F0R(add, n) {
                    int tmp = i;
                    int i = j; int j = tmp;
                    int cur = (i+add)%n;
                    int newVal = -1;
                    int newVal2 = -1;

                    if ((j > i && (i < cur && cur < j)) || (j < i && (cur > i || cur < j))) {
                        newVal = path[j][cur] + max(dp(cur, j, 0), dp(i, cur, 1)) - 1;
                    } else if (cur != i && cur != j) {
                        newVal2 = pathRev[j][cur] + max(dp(j, cur, 1), dp(cur, i, 0)) - 1;
                    }

                    int val = max(newVal, newVal2);
                    if (best < val) {
                        best = val;
                        bestIdx = i;
                    }
                }
            }

            reverse(all(radj[i]));
            int sub = 0;
            for (int j : radj[i]) {
                while (sub < (i-j+n)%n) {
                    int cur = (i-sub+n)%n;
                    //cout << j << "-->" << i << ": processed " << cur << endl;
                    sub++;
                    if (pathRev[i][cur] == 0) continue;
                    for (int nxt : adj[cur]) {
                        if ((cur >= i && (i < nxt && nxt < cur)) || (cur <= i && (nxt > i || nxt < cur))) {
                            pathRev[i][nxt] = max(pathRev[i][nxt], pathRev[i][cur]+1);
                        }
                    }
                }
                F0R(add, n) {
                    int tmp = i;
                    int i = j; int j = tmp;
                    int cur = (i+add)%n;
                    int newVal = -1;
                    int newVal2 = -1;

                    if ((j > i && (i < cur && cur < j)) || (j < i && (cur > i || cur < j))) {
                        newVal = path[j][cur] + max(dp(cur, j, 0), dp(i, cur, 1)) - 1;
                    } else if (cur != i && cur != j) {
                        newVal2 = pathRev[j][cur] + max(dp(j, cur, 1), dp(cur, i, 0)) - 1;
                    }

                    int val = max(newVal, newVal2);
                    if (best < val) {
                        best = val;
                        bestIdx = i;
                    }
                }
            }
        }
    }

    cout << best << endl;
    cout << bestIdx+1 << endl;

    return 0;
}

• Subtask 1: 40 / 100