제출 #1291801

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1291801		dubabuba	Tracks in the Snow (BOI13_tracks)	C++20	82.50 / 100	2099 ms	120728 KiB

tracks

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

typedef pair<int, int> pii;
#define ff first
#define ss second
#define MP make_pair

const int mxn = 4040;
int dis[mxn][mxn], n, m;
bool vis[mxn][mxn];
char c[mxn][mxn];

int di[] = {1, -1, 0, 0};
int dj[] = {0, 0, -1, 1};

void bfs(int si, int sj) {
    dis[si][sj] = 1;
    priority_queue<pair<int, pii>> pq;
    pq.push(MP(-1, MP(si, sj)));

    while(pq.size()) {
        int d = -pq.top().ff;
        int i = pq.top().ss.ff;
        int j = pq.top().ss.ss;
        pq.pop();

        if(c[i][j] == '.') continue;
        if(dis[i][j] != d) continue;
        if(vis[i][j]) continue;
        vis[i][j] = 1;

        for(int x = 0; x < 4; x++) {
            int I = i + di[x];
            int J = j + dj[x];
            if(c[I][J] == '.') continue;

            if(c[i][j] == c[I][J]) {
                dis[I][J] = min(dis[I][J], d);
                pq.push(MP(-d, MP(I, J)));
            }
            else {
                dis[I][J] = min(dis[I][J], d + 1);
                pq.push(MP(-d-1, MP(I, J)));
            }
        }
    }
}

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

    cin >> n >> m;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            cin >> c[i][j];
        }
    }

    for(int i = 1; i <= n; i++)
        c[i][0] = c[i][m + 1] = '.';
    for(int j = 1; j <= m; j++)
        c[0][j] = c[n + 1][j] = '.';

    memset(dis, 0x3f, sizeof dis);
    bfs(1, 1);

    int ans = 0;
    for(int i = 1; i <= n; i++)
    for(int j = 1; j <= m; j++)
        if(c[i][j] != '.')
            ans = max(ans, dis[i][j]);

    cout << ans << endl;
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 52.5 / 70