Submission #812155

#	Time	Username	Problem	Language	Result	Execution time	Memory
812155		devariaota	Tracks in the Snow (BOI13_tracks)	C++17	45.31 / 100	2091 ms	1048576 KiB

tracks

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

char grid[4005][4005], cur;
bool vis[4005][4005];
int h, w, n, cnt, ans = 0;

bool valid(int i, int j){
    return (i>=1 && i<=h && j>=1 && j<=w);
}

void dfs(int i, int j){
    cnt++;
    vis[i][j] = 1;
    if(!vis[i+1][j] && valid(i+1,j) && grid[i+1][j]==cur){
        grid[i+1][j] = (cur=='F' ? 'R' : 'F');
        dfs(i+1,j);
    }
    if(!vis[i][j+1] && valid(i,j+1) && grid[i][j+1]==cur){
        grid[i][j+1] = (cur=='F' ? 'R' : 'F');
        dfs(i,j+1);
    }
    if(!vis[i-1][j] && valid(i-1,j) && grid[i-1][j]==cur){
        grid[i-1][j] = (cur=='F' ? 'R' : 'F');
        dfs(i-1,j);
    }
    if(!vis[i][j-1] && valid(i,j-1) && grid[i][j-1]==cur){
        grid[i][j-1] = (cur=='F' ? 'R' : 'F');
        dfs(i,j-1);
    }
}

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

    cin>>h>>w;
    for(int i=1;i<=h;i++){
        for(int j=1;j<=w;j++){
            cin>>grid[i][j];
            if(grid[i][j] != '.') n++;
        }
    }
    if(grid[1][1] == '.') {
        cout<<"0\n";
        return 0;
    }


    while(cnt<n){
        cnt = 0;
        cur = grid[1][1];
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++) vis[i][j] = 0;
        }

        grid[1][1] = (cur=='F' ? 'R' : 'F');
        dfs(1,1);
        ++ans;
    }

    cout<<ans<<'\n';

    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 15.3125 / 70