Submission #804125

#	Time	Username	Problem	Language	Result	Execution time	Memory
804125		Dan4Life	Ideal city (IOI12_city)	C++17	55 / 100	148 ms	16736 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};
int dis[2010][2010], mp[2010][2010];

int bfs(int i, int X, int Y){
    queue<pair<int,int>> Q; Q.push({X,Y});
    vector<pair<int,int>> v; dis[X][Y]=0; int tot = 0;
    while(!empty(Q)){
        auto [x1,y1] = Q.front(); Q.pop();
        tot+=dis[x1][y1]*(mp[x1][y1]>=i); tot%=MOD;
        v.push_back({x1,y1});
        for(int k = 0; k < 4; k++){
            int x2 = x1+x[k], y2 = y1+y[k];
            if(x2<0 or y2<0 or !mp[x2][y2] or dis[x2][y2]!=-1) continue;
            dis[x2][y2] = dis[x1][y1]+1, Q.push({x2,y2});
        }
    }
    for(auto [x1,y1] : v) dis[x1][y1]=-1;
    return tot;
}

int DistanceSum(int N, int *X, int *Y) {
    if(N<=2000){
        vector<int> v; memset(dis,-1,sizeof(dis));
        for(int j : {0,1}){
            v.clear();
            for(int i = 0; i < N; i++) v.push_back(X[i]);
            sort(begin(v),end(v)); v.erase(unique(begin(v),end(v)),end(v));
            for(int i = 0; i < N; i++) 
                X[i] = (int)(lower_bound(begin(v),end(v),X[i])-begin(v)),
                swap(X[i],Y[i]);
        }
        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:29:17: warning: unused variable 'j' [-Wunused-variable]
   29 |         for(int j : {0,1}){
      |                 ^
city.cpp:45:13: warning: unused variable 'j' [-Wunused-variable]
   45 |     for(int j : {0,1}){
      |             ^

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