Submission #785681

#	Time	Username	Problem	Language	Result	Execution time	Memory
785681		lucas_joel_han	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	622 ms	122648 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
#define fi first
#define se second

const int INF = 1e9;
int dx[] = {-1, 0, 1, 0}, dy[] = {0, -1, 0, 1};

int main() {
	cin.tie(0)->sync_with_stdio(0);
	int N, M;
	cin >> N >> M;
	vector<vector<char>> v(N, vector<char>(M));
	for (int i = 0; i < N; i++) {
		string s;
		cin >> s;
		for (int j = 0; j < M; j++) {
			v[i][j] = s[j];
		}
	}
	vector<vector<int>> d(N, vector<int>(M, INF));
	d[0][0] = 1;
	deque<pii> q;
	q.push_front(pii(0, 0));
	while (!q.empty()) {
		pii cur = q.front();
		q.pop_front();
		for (int i = 0; i < 4; i++) {
			int x = cur.fi + dx[i], y = cur.se + dy[i];
			if (x < 0 || x >= N || y < 0 || y >= M || v[x][y] == '.') continue;
			bool weight = (v[x][y] != v[cur.fi][cur.se]);
			if (d[cur.fi][cur.se] + weight < d[x][y]) {
				d[x][y] = d[cur.fi][cur.se] + weight;
				if (weight) q.push_back(pii(x, y));
				else q.push_front(pii(x, y));
			}
		}
	}
	int sol = 0;
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < M; j++) {
			if (v[i][j] != '.') sol = max(sol, d[i][j]);
		}
	}
	cout << sol << '\n';
}

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