제출 #129210

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
129210		shashwatchandra	Tracks in the Snow (BOI13_tracks)	C++17	82.50 / 100	2130 ms	1011688 KiB

tracks

/*input
5 8
FFR.....
.FRRR...
.FFFFF..
..RRRFFR
.....FFF
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long 
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back

#define RE(i,n) for (int i = 1; i <= n; i++)
#define RED(i,n) for (int i = n; i > 0; i--)
#define REPS(i,n) for(int i = 1; (i*i) <= n; i++)
#define REP(i,n) for (int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for (int i = a; i < b; i++)
#define REPD(i,n) for (int i = n-1; i >= 0; i--)
#define FORD(i,a,b) for (int i = a; i >= b; i--)

#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout << *it << " "; cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x,y) cout << x << " " << y << endl;
#define debug3(x,y,z) cout << x << " " << y << " " << z << endl;

typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;

const int INF = 1e18+1;
const int MOD = 1e9+7;
const double PI = 3.14159265358979323846264338;

int raise(int a,int n,int m = MOD){
  if(n == 0)return 1;
  if(n == 1)return a;
  int x = 1;
    x *= raise(a,n/2,m);
    x %= m;
    x *= x;
    x %= m;
    if(n%2)x*= a;
    x %= m;
    return x;
}

int floor1(int n,int k){
    if(n%k == 0 || n >= 0)return n/k;
    return (n/k)-1;
}

int ceil1(int n,int k){
    return floor1(n+k-1,k);
}

const int N = 4001;
int a[N][N];
bool vis[N][N];
int comp[N][N];
vector<int> newvis;
int n,m;
vector<set<int> > adj;
int cur = 1;

pair<int,int> xd[] = {{-1,0},{0,-1},{1,0},{0,1}};

bool ok(int x,int y){
	return (x and y and (x <= n) and (y <= m));
}

void dfs(int i,int j){
	if(vis[i][j])return;
	vis[i][j] = 1;
	comp[i][j] = cur;
	REP(k,4){
		int ni = i+xd[k].f;
		int nj = j+xd[k].s;

		if(!ok(ni,nj))continue;
		if(a[i][j] != a[ni][nj])continue;
		dfs(ni,nj);
	}
}

int bfs(){
	newvis[1] = 1;
	queue<int> q;
	int ans = 1;
	q.push(1);
	while(!q.empty()){
		int u = q.front();q.pop();
		for(int v:adj[u]){
			if(newvis[v] != -1)continue;
			newvis[v] = newvis[u]+1;
			ans = max(ans,newvis[v]);
			q.push(v);
		}
	}
	return ans;
}


void solve(){
  	cin >> n >> m;
  	RE(i,n){
  		RE(j,m){
  			char o;cin >> o;
  			//cout << o;
  			if(o == '.'){vis[i][j] = 1;comp[i][j] = 0;continue;}
  			if(o == 'F')a[i][j] = 1;
  			else a[i][j] = 2;
  		}
  	//	cout << endl;
  	}
  	RE(i,n){
  		RE(j,m){
  			if(vis[i][j])continue;
  			dfs(i,j);
  			cur++;
  		}
  	}

  	newvis.resize(cur,-1);
  	adj.resize(cur);

  	RE(i,n){
  		RE(j,m){
  			if(!comp[i][j])continue;
  			REP(k,4){
				int ni = i+xd[k].f;
				int nj = j+xd[k].s;
				if(ok(ni,nj) and comp[ni][nj] and comp[ni][nj] != comp[i][j]){
					adj[comp[i][j]].insert(comp[ni][nj]);
				}
			}	
  		}
  	}
  	cout << bfs();
}

signed main(){
  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  //freopen(".in","r",stdin);freopen(".out","w",stdout);
  int t = 1;
  //cin >> t;
  while(t--){
    solve();
  }
  return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 52.5 / 70