Submission #715640

#	Time	Username	Problem	Language	Result	Execution time	Memory
715640		fatemetmhr	Tracks in the Snow (BOI13_tracks)	C++17	97.81 / 100	618 ms	1048576 KiB

tracks

// ~ Be Name Khoda ~

#include <bits/stdc++.h>
//#pragma GCC optimize ("Ofast")
//#pragma GCC target("avx2")
//#pragma GCC optimize("unroll-loops,O3")

using namespace std;

typedef long long ll;

#define pb       push_back
#define mp       make_pair
#define all(x)   x.begin(), x.end()
#define fi       first
#define se       second

const int maxn  =  1e6   + 10;
const int maxn5 =  4e3   + 5;
const int maxnt =  1.2e6 + 10;
const int maxn3 =  1e3   + 10;
const int mod   =  1e9   +  7;
const ll  inf   =  1e18;

int n, m, indtmp = 0, indnxt = 0;
bool mark[maxn5][maxn5];
pair<int, int> nxt[maxn5 * maxn5 * 4], tmp[maxn5 * maxn5 * 4];
string s[maxn5];

void dfs(int x, int y){
    mark[x][y] = true;
    if(x && !mark[x - 1][y] && s[x - 1][y] != '.'){
        if(s[x - 1][y] == s[x][y])
            dfs(x - 1, y);
        else
            nxt[indnxt++] = {x - 1, y};
    }
    if(x + 1 < n && !mark[x + 1][y] && s[x + 1][y] != '.'){
        if(s[x + 1][y] == s[x][y])
            dfs(x + 1, y);
        else
            nxt[indnxt++] = {x + 1, y};
    }
    if(y && !mark[x][y - 1] && s[x][y - 1] != '.'){
        if(s[x][y - 1] == s[x][y])
            dfs(x, y - 1);
        else
            nxt[indnxt++] = {x, y - 1};
    }
    if(y + 1 < m && !mark[x][y + 1] && s[x][y + 1] != '.'){
        if(s[x][y + 1] == s[x][y])
            dfs(x, y + 1);
        else
            nxt[indnxt++] = {x, y + 1};
    }
}

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(0);

    cin >> n >> m;
    for(int i = 0; i < n; i++)
        cin >> s[i];
    dfs(0, 0);
    int ans = 1;
    while(indnxt){
        ans++;
        indtmp = indnxt;
        for(int i = 0; i < indnxt; i++)
            tmp[i] = nxt[i];
        indnxt = 0;
        for(int i = 0; i < indtmp; i++) if(!mark[tmp[i].fi][tmp[i].se])
            dfs(tmp[i].fi, tmp[i].se);
    }
    cout << ans << endl;
}

• Subtask 1: 30 / 30
• Subtask 2: 67.8125 / 70