Submission #1191979

#	Time	Username	Problem	Language	Result	Execution time	Memory
1191979		ChuanChen	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	494 ms	132864 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;
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

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;
	marc[1][1] = true;
	while(!dq.empty()){
		auto [x, y] = dq.front();
		dq.pop_front();
		ans = max(ans, d[x][y]);
		for(int i = 0; i < 4; i++){
			int nx = x+dx[i], ny = y+dy[i];
			if(c[nx][ny] == '.' || !inbound(nx, ny) || marc[nx][ny]) continue;

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

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