Submission #96945

#	Time	Username	Problem	Language	Result	Execution time	Memory
96945		dalgerok	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	1805 ms	131204 KiB

tracks

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




const int N = 4005, INF = 2e9, dx[] = {-1, 0, 1, 0}, dy[] = {0, -1, 0, 1};




int n, m, d[N][N];
char a[N][N];

inline bool check(int x, int y){
    return 1 <= x && x <= n && 1 <= y && y <= m;
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            cin >> a[i][j];
            d[i][j] = INF;
        }
    }
    deque < pair < int, int > > q;
    q.push_back(make_pair(1, 1));
    d[1][1] = 1;
    while(!q.empty()){
        int x = q.front().first,
            y = q.front().second;
        q.pop_front();
        for(int i = 0; i < 4; i++){
            int xx = x + dx[i],
                yy = y + dy[i];
            if(check(xx, yy) && a[xx][yy] != '.'){
                int val = d[x][y] + (a[x][y] != a[xx][yy]);
                if(d[xx][yy] > val){
                    d[xx][yy] = val;
                    if(a[x][y] == a[xx][yy]){
                        q.push_front(make_pair(xx, yy));
                    }
                    else{
                        q.push_back(make_pair(xx, yy));
                    }
                }
            }
        }
    }
    int ans = 0;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(a[i][j] != '.'){
                ans = max(ans, d[i][j]);
            }
        }
    }
    cout << ans << "\n";
}

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