Submission #715647

#	Time	Username	Problem	Language	Result	Execution time	Memory
715647		arashMLG	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	823 ms	133196 KiB

tracks

#include<bits/stdc++.h>
#ifdef LOCAL
#include "Essentials/algo/debug.h"
#else
#define debug(...) 42
#endif
using namespace std;

//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

typedef long long     ll;
typedef long double   ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll>   pll;

const int N = 4000 + 23;
const ll mod = 1e9+7;
const int LOG = 23;
const ll inf = 1e18;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

#define F           first
#define S           second
#define pb          push_back
#define ms(x,y)     memset((x) , (y) , sizeof (x))
#define done        return cout<<endl , 0;
#define kill(x)     cout<<x<<endl, exit(0);
#define isIn(x,s,e) ((x) >= (s) && (x) <= e)
#define all(x)      x.begin(),x.end()
#define sz(x)       (int)x.size()
#define pc(x)       __builtin_popcount(x)
#define ctz(x)      __builtin_ctz(x)
#define MinHeap(x)  priority_queue<x, vector<x> , greater<x> >
#define MaxHeap(x)  priority_queue<x, vector<x>>
//#define int      ll

ll pw(ll a, ll b, ll md = mod){ll res = 1; while(b){if(b&1){res=(a*res)%md;}a=(a*a)%md;b>>=1;}return(res);}

int h,w; 
char a[N][N];
bool mark[N][N];
int dx[] = {1,0,-1,0}, dy[] = {0,1,0,-1};
int dist[N][N];
int ans = 0;
deque<pii> Q;

void bfs() {
    Q.pb({0,0});
    mark[0][0] = true;
    dist[0][0] = 1;
    while(sz(Q)) {
        auto [x,y] = Q.back(); Q.pop_back();
        ans = max(ans,dist[x][y]);
        for(int i = 0 ;i < 4; i ++) {
            int x2 = x + dx[i] , y2= y + dy[i];
            if(isIn(x2,0,h-1) && isIn(y2,0,w-1) && !mark[x2][y2]) {
                if(a[x2][y2] == a[x][y]) {
                    dist[x2][y2] = dist[x][y];
                    mark[x2][y2] = true;
                    Q.push_back({x2,y2});
                } else {
                    dist[x2][y2] = dist[x][y] + 1;
                    mark[x2][y2] = true;
                    Q.push_front({x2,y2});
                }
            }
        }
    }
}
int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    cin>>h>>w;
    for(int i = 0 ;i < h ; i ++){
        for(int j = 0 ; j< w; j++) {
            cin>>a[i][j];
            if(a[i][j] == '.') {
                mark[i][j] = true;
            }
        }
    }
    bfs();
    cout<<ans<<'\n';
    done;   
}

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