典型双指针算法

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 1e5 + 10;
int n,m,x;
int a[N],b[N];

int main(){
    scanf("%d%d%d",&n,&m,&x);
    for(int i = 0;i < n;++i)    scanf("%d",&a[i]);
    for(int i = 0;i < m;++i)    scanf("%d",&b[i]);
    for(int i = 0,j = m - 1;i < n;++i){
        while(j >= 0 && a[i] + b[j] > x)   j--;
        if(j >= 0 && a[i] + b[j] == x)  printf("%d %d",i,j);
    }
    return 0;
}