Submission #440273

#	Time	Username	Problem	Language	Result	Execution time	Memory
440273		penguinhacker	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	831 ms	152196 KiB

tracks

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

#define ll long long
#define ar array

const int mxN=4000, di[4]={1, -1, 0, 0}, dj[4]={0, 0, 1, -1};
int n, m, d[mxN][mxN], ans;
string g[mxN];
bool vis[mxN][mxN];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n >> m;
	for (int i=0; i<n; ++i)
		cin >> g[i];
	memset(d, 0x3f, sizeof(d));
	d[0][0]=1;
	deque<ar<int, 2>> q={{0, 0}};
	while(q.size()) {
		int i=q.front()[0], j=q.front()[1];
		q.pop_front();
		if (vis[i][j])
			continue;
		vis[i][j]=1;
		ans=max(ans, d[i][j]);
		for (int k=0; k<4; ++k) {
			int ni=i+di[k], nj=j+dj[k];
			if (0<=ni&&ni<n&&0<=nj&&nj<m&&!vis[ni][nj]&&g[ni][nj]^'.') {
				if (g[i][j]==g[ni][nj]&&d[i][j]<d[ni][nj]) {
					d[ni][nj]=d[i][j];
					q.push_front({ni, nj});
				} else if (g[i][j]^g[ni][nj]&&d[i][j]+1<d[ni][nj]) {
					d[ni][nj]=d[i][j]+1;
					q.push_back({ni, nj});
				}
			}
		}
	}
	cout << ans;
	return 0;
}

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