Campus

#include<stdio.h>
typedef long long int ll;

ll abs(ll a){
    return (a < 0 ? a*-1:a);
}

struct dorm{
    ll I;
    ll J;
    ll s;
};

int main()
{
    int n;
    scanf("%d",&n);
    dorm d[n];
    for(int i = 0 ; i < n ; i ++){
        scanf("%lld %lld %lld",&d[i].I,&d[i].J,&d[i].s);
    }
    ll posI,posJ;
    ll sumI,sumJ;
    // I
//  printf("Bsearch I : ");
    ll L = 1 , R = 1e9;
    while(L <= R){
        ll m = (L+R)/2;
    //  printf("%lld ",m);
        ll a = m - 1 , b = m , c = m + 1;
        ll sa = 0 , sb = 0 , sc = 0;
        for(int i = 0 ; i < n ; i ++){
            sa += abs(a - d[i].I)*d[i].s;
            sb += abs(b - d[i].I)*d[i].s;
            sc += abs(c - d[i].I)*d[i].s;
        }
        if(sa >= sb && sb <= sc){
            posI = m;
            sumI = sb;
            break;
        }
        else if(sa > sb && sb > sc){
            L = m + 1;
        }
        else if(sa < sb && sb < sc){
            R = m - 1;
        }
        else{
    //      printf("Error %lld %lld %lld <- %lld\n",sa,sb,sc,m);
            return -1;
        }
    }

    //J
    L = 1 , R = 1e9;
//  printf("\nBsearch J : ");
    while(L <= R){
        ll m = (L+R)/2;
    //  printf("%lld ",m);
        ll a = m - 1 , b = m , c = m + 1;
        ll sa = 0 , sb = 0 , sc = 0;
        for(int i = 0 ; i < n ; i ++){
            sa += abs(a - d[i].J)*d[i].s;
            sb += abs(b - d[i].J)*d[i].s;
            sc += abs(c - d[i].J)*d[i].s;
        }
        if(sa >= sb && sb <= sc){
            posJ = m;
            sumJ = sb;
            break;
        }
        else if(sa > sb && sb > sc){
            L = m + 1;
        }
        else if(sa < sb && sb < sc){
            R = m - 1;
        }
        else{
    //      printf("Error %lld %lld %lld <- %lld\n",sa,sb,sc,m);
            return -1;
        }
    }

    printf("%lld",sumI+sumJ);
    return 0;
}