Submission #127066

#	Time	Username	Problem	Language	Result	Execution time	Memory
127066		eriksuenderhauf	Sailing Race (CEOI12_race)	C++11	100 / 100	2470 ms	7544 KiB

race

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5e2 + 2;
const int INF = 1e9 + 7;
int ans[MAXN], mx[MAXN][MAXN][2];
int dp[MAXN][MAXN][2], dp2[MAXN][MAXN][2];
bool adj[MAXN][MAXN];
int nex[MAXN][MAXN];
int n;
 
inline bool between(int l, int r, int x) {
    if (l > r)
        return l < x || x < r;
    return l < x && x < r;
}
 
int solve(int l, int r, int k) {// path ends at r, interval at l
    if (dp[l][r][k] != -1) return dp[l][r][k];
    int &ret = dp[l][r][k];
    ret = 0;
    int lo = k ? r : l;
    int hi = l ^ r ^ lo;
    for (int i=1; i <= nex[r][0]; i++)
        if (between(lo, hi, nex[r][i]))
            ret = max(ret, max(solve(r, nex[r][i], k^1),  solve(l, nex[r][i], k)) + 1);
    return ret;
}
 
int f2(int l, int r, int k) {
    if (l == r) return 0;
    if (dp2[l][r][k] != -1) return dp2[l][r][k];
    int ret = adj[l][r] ? 0 : -INF;
    int lo = k ? r : l;
    int hi = l ^ r ^ lo;
    for (int i=1; i <= nex[l][0]; i++)
        if (between(lo, hi, nex[l][i]))
            ret = max(ret, f2(nex[l][i], r, k));
    return dp2[l][r][k] = ret + 1;
}
 
int b[MAXN];

int main() {
    memset(dp, -1, sizeof dp);
    memset(dp2, -1, sizeof dp2);
    int k;
    scanf("%d %d", &n, &k);
    for (int i = 1; i <= n; i++) {
        b[i] = i;
        int x;
        while (1) {
            scanf("%d", &x);
            if (x == 0)
                break;
            adj[i][x] = 1;
            nex[i][++nex[i][0]] = x;
        }
    }
    for (int i = 1; i <= n; i++)
        for (int j=1; j <= nex[i][0]; j++)
            ans[i] = max(ans[i], max(solve(i, nex[i][j], 0), solve(i, nex[i][j], 1)) + 1);
    mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
    shuffle(b+1,b+n+1, rng);
    if (k == 1) for (int ii = 1; ii <= n; ii++) {
        int i = b[ii];
        memset(mx, 0, sizeof mx);
        for (int x = (i%n) + 1; x != i; x = (x%n) + 1)
            for (int y = (x+1)%n + 1; y != i; y = (y%n) + 1) {
                mx[x][y][0] = mx[x][(y+n-2)%n + 1][0];
                if (adj[i][(y+n-2)%n + 1])
                    mx[x][y][0] = max(mx[x][y][0], solve(x,(y+n-2)%n + 1,0) + 1);
            }
        for (int x = (i+n-2)%n+1; x != i; x = (x-2+n)%n+1)
            for (int y = (x+2*n-3)%n+1; y != i; y = (y-2+n)%n+1) {
                mx[y][x][1] = mx[y%n+1][x][1];
                if (adj[i][y%n+1])
                    mx[y][x][1] = max(mx[y][x][1], solve(x,y%n+1,1) + 1);
            }
 
        for (int l = i%n+1; l != (i+2*n-3)%n+1; l = (l%n) + 1)
            for (int j = (l+1)%n+1; j != i; j = (j%n) + 1) {
                if (adj[l][j])
                    ans[l] = max(ans[l], max(f2(j, i, 0) + mx[l][j][0], f2(j, i, 0) + mx[l][j][1]) + 1);
                if (adj[j][l])
                    ans[j] = max(ans[j], max(f2(l, i, 1) + mx[l][j][0], f2(l, i, 1) + mx[l][j][1]) + 1);
            }
        if (ii > 350) break;
    }
    int ind = 0;
    for (int i = 1; i <= n; i++)
        if (ans[ind] < ans[i])
            ind = i;
    printf("%d\n%d\n", ans[ind], ind);
    return 0;
}

Compilation message (stderr)

race.cpp: In function 'int main()':
race.cpp:48:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &k);
     ~~~~~^~~~~~~~~~~~~~~~~
race.cpp:53:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d", &x);
             ~~~~~^~~~~~~~~~

• Subtask 1: 100 / 100