Submission #675787

#	Time	Username	Problem	Language	Result	Execution time	Memory
675787		NONTAC	Tracks in the Snow (BOI13_tracks)	C++11	100 / 100	1439 ms	118952 KiB

tracks

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

typedef pair<int, int> ii;

int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};
int n, m;
char grid[4002][4002];
int d[4002][4002];
int ans = 0;

bool same(char c1, char c2)
{
    if(c1 != c2) return true;
    return false;
}

void bfs(int si, int sj)
{
    deque<ii> dq;
    d[si][sj] = 1;
    dq.push_front(ii(si, sj));
    while(!dq.empty()){
        int ui = dq.front().first, uj = dq.front().second;
        dq.pop_front();
        ans = max(ans, d[ui][uj]);
        for(int i = 0; i < 4; i++){
            int vi = ui + dx[i], vj = uj + dy[i];
            int w = same(grid[ui][uj], grid[vi][vj]);
            if(vi < 1 || vi > n || vj < 1 || vj > m) continue;
            if(d[vi][vj] == 0 && grid[vi][vj] != '.'){
                d[vi][vj] = d[ui][uj] + w;
                if(w == 0){
                    dq.push_front(ii(vi, vj));
                }
                else{
                    dq.push_back(ii(vi, vj));
                }
            }
        }
    }
}

int main()
{
    //freopen("test.in","r",stdin);
    //freopen("test.out","w",stdout);

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

    bfs(1, 1);

    cout<<ans;

    return 0;
}

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