Submission #715171

#	Time	Username	Problem	Language	Result	Execution time	Memory
715171		radal	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	475 ms	119360 KiB

tracks

#include <bits/stdc++.h>
//#pragma GCC target("sse,sse2,avx2")
#pragma GCC optimize("unroll-loops,O3")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
constexpr int N = 4e3+20,mod = 998244353;
constexpr ll inf = 1e9+10;
inline int mkay(int a,int b){
    if (a+b >= mod) return a+b-mod;
    if (a+b < 0) return a+b+mod;
    return a+b;
}
 
inline int poww(int a,int k){
    if (k < 0) return 0;
    int z = 1;
    while (k){
        if (k&1) z = 1ll*z*a%mod;
        a = 1ll*a*a%mod;
        k >>= 1;
    } 
    return z; 
}

int d[N][N];
string s[N];
int n,m;
pll ja[4] = {{1,0},{-1,0},{0,1},{0,-1}};

inline bool isval(int i,int j){
	if (min(i,j) < 0 || i >= n || j >= m || s[i][j] == '.') return 0;
	return 1;
}

int bfs(){
	deque<pll> q;
	q.pb({0,0});
	d[0][0] = 1;
	int mx = 0;
	while (!q.empty()){
		pll p = q.front();
		q.pop_front();
		int x = p.X,y = p.Y;
		mx = max(mx,d[x][y]);
		rep(i,0,4){
			int x2 = x + ja[i].X,y2 = y + ja[i].Y;
			if (isval(x2,y2) && !d[x2][y2]){
				if (s[x2][y2] == s[x][y]){
					d[x2][y2] = d[x][y];
					q.push_front({x2,y2});
				}
				else{
					d[x2][y2] = d[x][y] + 1;
					q.pb({x2,y2});
				}
			}
		}
	}
	return mx;
}

int main(){
	ios :: sync_with_stdio(0); cin.tie(0);  cout.tie(0);
	cin >> n >> m;
	rep(i,0,n) cin >> s[i];
	cout << bfs() << endl;
}

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