Submission #804090

#	Time	Username	Problem	Language	Result	Execution time	Memory
804090		Dan4Life	Ideal city (IOI12_city)	C++17	34 / 100	1004 ms	2012 KiB

city

#include <bits/stdc++.h>
using namespace std;
using  ll = long long;
const ll MOD = (ll)1e9;
int x[] = {1,-1,0,0};
int y[] = {0,0,1,-1};
unordered_map<int,unordered_map<int,int>> dis,mp;
int bfs(int i, int X, int Y){
    queue<pair<int,int>> Q; Q.push({X,Y}); 
    dis[X][Y]=0; dis.clear(); int tot = 0;
    while(!empty(Q)){
        auto [x1,y1] = Q.front(); Q.pop();
        tot+=dis[x1][y1]*(mp[x1][y1]>=i); tot%=MOD;
        for(int k = 0; k < 4; k++){
            int x2 = x1+x[k], y2 = y1+y[k];
            if(mp[x2].find(y2)==mp[x2].end()) continue;
            if(dis[x2].find(y2)==dis[x2].end()){
                dis[x2][y2] = dis[x1][y1]+1;
                Q.push({x2,y2});
            }
        }
    }
    return tot;
}

int DistanceSum(int N, int *X, int *Y) {
    if(N<=2000){
        ll ans = 0;
        for(int i = 0; i < N; i++) 
            mp[X[i]][Y[i]]=i+1;
        for(int i = 0; i < N; i++)
            ans+=bfs(i+1, X[i],Y[i]),ans%=MOD;
        return ans;
    }
    ll ans = 0, tot = 0; 
    sort(X,X+N), sort(Y,Y+N);
    for(int j : {0,1}){
        tot = 0; sort(X,X+N);
        for(ll i = 0; i < N; i++){
            ans+=(1ll*X[i]*i-tot+MOD)%MOD;
            tot+=X[i], tot%=MOD; ans%=MOD;swap(X[i],Y[i]);
        }
    }
    return (int)ans;
}

Compilation message (stderr)

city.cpp: In function 'int DistanceSum(int, int*, int*)':
city.cpp:37:13: warning: unused variable 'j' [-Wunused-variable]
   37 |     for(int j : {0,1}){
      |             ^

• Subtask 1: 11 / 11
• Subtask 2: 0 / 21
• Subtask 3: 23 / 23
• Subtask 4: 0 / 45