Submission #1191976

#	Time	Username	Problem	Language	Result	Execution time	Memory
1191976		ChuanChen	Tracks in the Snow (BOI13_tracks)	C++20	11.56 / 100	467 ms	97900 KiB

tracks

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

#define ss second
#define ff first
typedef pair<int, int> pii;

const int lim = 4e3+5;
char c[lim][lim];
int d[lim][lim];
bool marc[lim][lim];
int H, W, ans;

bool inbound(int x, int y){
	return 1<=x&&x<=H && 1<=y&&y<=W;
}

int main(){
    cin.tie(0)->sync_with_stdio(0);
	cin >> H >> W;
	for(int i = 1; i <= H; i++){
		for(int j = 1; j <= W; j++){
			cin >> c[i][j];
		}
	}

	deque<pii> dq;
	dq.push_back({1, 1});
	d[1][1] = 1;
	int dx[] = {1, 0, -1, 0};
	int dy[] = {0, 1, 0, -1};
	while(!dq.empty()){
		auto [x, y] = dq.front();
		dq.pop_front();
		marc[x][y] = true;
		ans = max(ans, d[x][y]);
		for(int i = 0; i < 3; i++){
			int nx = x+dx[i], ny = y+dy[i];
			if(c[nx][ny] == '.' || !inbound(nx, ny) || marc[nx][ny]) continue;

			if(d[nx][ny] == 0){
				if(c[nx][ny] == c[x][y]){
					d[nx][ny] = d[x][y];
					dq.push_front({nx, ny});
				}
				else{
					d[nx][ny] = d[x][y]+1;
					dq.push_back({nx, ny});
				}
			}
		}
	}
	cout << ans << '\n';
}

• Subtask 1: 5 / 30
• Subtask 2: 6.5625 / 70