(White Book Training Program) fig 1152 4 values whose sum is 0 (midway encounter ..)

Subject address: Ultraviolet A 1152

First, enumerate the sum of set a and Set B, and then enumerate the sum of set C and set D to see how many values are opposite to each other. Question. You can use binary to find the stored value.

The Code is as follows:

#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;int a[5000], b[5000], c[6000], d[6000], p[17000000];int main(){    int t, n, m, ans, i, j, k;    scanf("%d",&t);    while(t--)    {        scanf("%d",&n);        m=0;        for(i=0;i<n;i++)        {            scanf("%d%d%d%d",&a[i],&b[i],&c[i],&d[i]);        }        for(i=0;i<n;i++)        {            for(j=0;j<n;j++)            {                p[m++]=a[i]+b[j];            }        }        sort(p,p+m);        int low, high, mid;        ans=0;        for(i=0;i<n;i++)        {            for(j=0;j<n;j++)            {                int x=-c[i]-d[j];                low=0, high=m-1;                while(low<=high)                {                    mid=low+high>>1;                    if(p[mid]>x) high=mid-1;                    else if(p[mid]<x) low=mid+1;                    else                    {                        for(k=mid;k>=0;k--)                        {                            if(p[k]==x)                            {                                ans++;                            }                            else                                break;                        }                        for(k=mid+1;k<m;k++)                        {                            if(p[k]==x)                            {                                ans++;                            }                            else                                break;                        }                        break;                    }                }            }        }        printf("%d\n",ans);        if(t)            puts("");    }    return 0;}

(White Book Training Program) fig 1152 4 values whose sum is 0 (midway encounter ..)