利用了两个数组都是从小到大排序的，然后双指针的方法就会很简单了

#include <iostream>

using namespace std;

const int N = 100010;
int a[N], b[N];
int m, n, x;

int main()
{
   cin >> n >> m >> x;
   for(int i = 0; i < n; i ++ )  cin >> a[i];
   for(int i = 0; i < m; i ++ )  cin >> b[i];
   int i = 0, j = m - 1;
   while(a[i] + b[j] != x)
   {
       while(a[i] + b[j] > x) j --;
       while(a[i] + b[j] < x) i ++; 
   }
   cout << i << " " << j <<endl;
}