Submission #910932

#	Time	Username	Problem	Language	Result	Execution time	Memory
910932		oblantis	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	502 ms	148952 KiB

tracks

#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#pragma GCC optimize("O3,unroll-all-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define all(v) v.begin(), v.end()
#define pb push_back
#define ss second
#define ff first
#define vt vector
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<int, int> pii;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
const int inf = 1e9;
const int mod = 1e9+7;
const int maxn = 4e3 + 2;
char a[maxn][maxn];
bool was[maxn][maxn];
int dp[maxn][maxn];
deque<pii> q;
void go(int x, int y, char s, int wt){
	if(a[x][y] != s)dp[x][y] = wt + 1, q.push_back({x, y});
	else dp[x][y] = wt, q.push_front({x, y});
	was[x][y] = 1;
}
void solve() {
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; i++){
		was[i][0] = was[i][m + 1] = 1;
		for(int j = 1; j <= m; j++){
			cin >> a[i][j];
			if(a[i][j] == '.')was[i][j] = 1;
		}
	}
	for(int i = 1; i <= m; i++)was[0][i] = was[n + 1][i] = 1;
	int ans = 1;
	char s = a[n][m];
	go(n, m, s, 1);
	while(!q.empty()){
		pii nw = q.front();
		q.pop_front();
		int x = nw.ff, y = nw.ss;
		ans = dp[x][y];
		s = a[x][y];
		if(!was[x - 1][y])go(x - 1, y, s, ans);
		if(!was[x + 1][y])go(x + 1, y, s, ans);
		if(!was[x][y - 1])go(x, y - 1, s, ans);
		if(!was[x][y + 1])go(x, y + 1, s, ans);
	}
	cout << ans;
}
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int times = 1;
	//cin >> times;
	for(int i = 1; i <= times; i++) {
		solve();
	}
	return 0;
}

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