C language sorting -- Can you find it? (Hdu 2141)

C language sorting -- Can you find it? (Hdu 2141)
Problem Description Give you three sequences of numbers A, B, C, then we give you a number X. now you need to calculate if you can find the three numbers Ai, Bj, Ck, which satisfy the formula Ai + Bj + Ck = X.
Input There are invalid cases. every data case is described as followed: In the first line there are three integers L, N, M, in the second line there are L integers represent the sequence, in the third line there are N integers represent the sequences B, in the forth line there are M integers represent the sequence C. in the same th line there is an integer S represents there are S integers X to be calculated. 1 <= L, N, M <= 500, 1 <= S <= 1000. all the integers are 32-integers.
Output For each case, firstly you have to print the case number as the form "Case d:", then for the S queries, you calculate if the formula can be satisfied or not. if satisfied, you print "YES", otherwise print "NO ".
Sample Input

3 3 31 2 31 2 31 2 331410

Sample Output

Case 1:NOYESNO

The first row of input data is three numbers, indicating the size of the three arrays. (the maximum size of the three arrays is 500.) The next three rows are the numbers of the three arrays. then, enter an integer n in the fourth row to indicate the next n rows of test data. each test data is an integer m. it is required that the sum of the numbers (three in total) of each array in the preceding three arrays is equal to the m value of the test data. if YES is found, NO is output. If NO such three numbers exist, NO is output.

General idea:
Because each array of the data given by the question has a maximum of 500 elements, if the three for loops are 500*500*500, it will definitely time out, (Let's call the first, second, and third arrays a, B, and c arrays here.) At this time, we can sort the c array and enumerate a with two for loops, B is used to search for all the combined k and k in the array c. in this way, the maximum time is 500*500 * log500 ≈ 2250000 or in, the number of m-c [I] in an array composed of k in the array 'B' is searched in binary form (the code below is ).
The Code is as follows:

#include 
 
  #include using namespace std;int a[501],b[501],m[250001],c[501],flag;void find(int a[],int b,int n){    int left,right,mid;    left=0,right=n-1;    while(left<=right)    {        mid=(left+right)/2;        if(a[mid]==b)        {            flag=1;            break;        }        else if(a[mid]>b)            right=mid-1;        else            left=mid+1;    }}int main(){    int i,j,k,n1,n2,n3,n4,ci=0;    while(scanf("%d%d%d",&n1,&n2,&n3)!=EOF)    {        ci++;        for(i=0;i