제출 #1172897

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1172897		nguyenkhangninh99	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	745 ms	258652 KiB

tracks

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

#define int long long

const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, 1, -1};
const int maxn = 4005;
char a[maxn][maxn];
int d[maxn][maxn];

void solve(){
    int n, m; cin >> n >> m;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++) cin >> a[i][j];
    }
    
    deque<array<int, 3>> dq;
    dq.push_back({1, 1, 1});
  
    vector<vector<int>> d(n + 1, vector<int>(m + 1, 1e9));

    d[1][1] = 1;
    while(!dq.empty()){
        auto[curd, x, y] = dq.front();
        dq.pop_front();
        if (curd > d[x][y]) continue;
        for (int k = 0; k < 4; k++){
            int r = x + dx[k], c = y + dy[k];
            if (r < 1 || c < 1 || r > n || c > m || a[r][c] == '.') continue;
            if (d[r][c] > d[x][y] + (a[r][c] != a[x][y])) {
                d[r][c] = d[x][y] + (a[r][c] != a[x][y]);
                if (a[r][c] == a[x][y]) dq.push_front({d[r][c], r, c});
                else dq.push_back({d[r][c], r, c});
            }
        }
     }

    int res = 0;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(d[i][j] < 5e8) res = max(res, d[i][j]);
        }
    }
    cout << res;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
 
    solve();
}

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