제출 #59162

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
59162		Benq	Tracks in the Snow (BOI13_tracks)	C++14	95.63 / 100	2100 ms	828132 KiB

tracks

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)

#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()

const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 4000*4000;


template<int SZ> struct DSU {
    int par[SZ], sz[SZ];
    DSU() {
        F0R(i,SZ) par[i] = i, sz[i] = 1;
    }
    
    int get(int x) { // path compression
    	if (par[x] != x) par[x] = get(par[x]);
    	return par[x];
    }
    
    bool unite(int x, int y) { // union-by-rank
    	x = get(x), y = get(y);
    	if (x == y) return 0;
    	if (sz[x] < sz[y]) swap(x,y);
    	sz[x] += sz[y], par[y] = x;
    	return 1;
    }
};

DSU<MX> D;
int H,W, dist[MX];
string g[4000];
vi adj[MX];

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> H >> W;
    F0R(i,H) cin >> g[i];
    F0R(i,H) F0R(j,W-1) if (g[i][j] == g[i][j+1]) D.unite(W*i+j,W*i+j+1);
    F0R(i,H-1) F0R(j,W) if (g[i][j] == g[i+1][j]) D.unite(W*i+j,W*(i+1)+j);
    F0R(i,H) F0R(j,W-1) if (g[i][j] != g[i][j+1]) {
        if (g[i][j] == '.' || g[i][j+1] == '.') continue;
        int a = D.get(W*i+j), b = D.get(W*i+j+1);
        adj[a].pb(b), adj[b].pb(a);
    }
    
    F0R(i,H-1) F0R(j,W) if (g[i][j] != g[i+1][j]) {
        if (g[i][j] == '.' || g[i+1][j] == '.') continue;
        int a = D.get(W*i+j), b = D.get(W*(i+1)+j);
        adj[a].pb(b), adj[b].pb(a);
    }
    
    F0R(i,MX) dist[i] = MOD;
    int x = D.get(0); dist[x] = 0;
    queue<int> q; q.push(x);
    
    int ans = 0;
    while (sz(q)) {
        int x = q.front(); q.pop();
        for (int i: adj[x]) if (dist[i] == MOD) {
            dist[i] = dist[x]+1;
            ans = max(ans,dist[i]);
            q.push(i);
        }
    }
    cout << ans+1;
}

/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( ) 
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/

• Subtask 1: 30 / 30
• Subtask 2: 65.625 / 70