和为定值的两个数组元素

在数组中找到和为定值的两个数，返回数组下标。
这个题目就是一个排序的问题，但是不能改变数组，用快排的方式存储数组的索引值即可，上代码。

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <vector>
using namespace std;

void quicksort_index(int *arr, int *index, int low, int high)
{
    if (low >= high)
        return;
    int i = low;
    int j = high;
    int tmp = index[j];
    int val = arr[index[j]];
    while (i < j)
    {
        while (i < j && arr[index[i]] <= val)
            i++;
        index[j] = index[i];
        while (i < j && arr[index[j]] > val)
            j--;
        index[i] = index[j];
    }
    index[i] = tmp;
    quicksort_index(arr, index, low, i-1);
    quicksort_index(arr, index, i+1, high);
}

void get_two_sum_index(int *arr, int *index_arr, int len, int two_sum, std::vector<int> &ivec)
{
    int start_index = 0;
    int end_index = len;
    int i = 0;
    int j = 0;
    ivec.clear();
    while (start_index < end_index)
    {
        i = index_arr[start_index];
        j = index_arr[end_index];
        if (two_sum == arr[i] + arr[j]) {
            ivec.push_back(i);
            ivec.push_back(j);
            start_index++;
            end_index--;
        } else if (two_sum > arr[i] + arr[j]) {
            start_index++;
        } else {
            end_index--;
        }
    }
}

int main(int argc, char *argv[])
{
    //int arr[] = {1, -2, 3, 10, -4, 7, 2, -5};
    int arr[] = {102, 21, 39, 210, 94, 72, 2, 5, 167};
    int len = sizeof(arr) / sizeof(int);
    std::cout << "array data" << std::endl;
    int *index_arr = new int[len];
    int i = 0;
    for (i = 0; i < len; i++)
    {
        std::cout << arr[i] << " ";
        index_arr[i] = i;
    }
    std::cout << std::endl;
    quicksort_index(arr, index_arr, 0, len-1);

    for (i = 0; i < len; i++)
    {
        std::cout << arr[i] << " ";
    }
    std::cout << std::endl;

    for (i = 0; i < len; i++)
    {
        std::cout << arr[index_arr[i]] << " ";
    }
    std::cout << std::endl;

    int two_sum = 111;
    std::cout << "to get two sum: " << two_sum << std::endl;
    std::vector<int> ivec;
    get_two_sum_index(arr, index_arr, len-1, two_sum, ivec);
    std::vector<int>::iterator iter;
    int min_val;
    int max_val;
    for (iter = ivec.begin(); iter != ivec.end(); iter++)
    {
        std::cout << "[min_index, max_index]: " << *iter << ", ";
        min_val = arr[*iter];
        iter++;
        max_val = arr[*iter];
        std::cout << *iter << std::endl;
        std::cout << "[min_val, max_val]: " << min_val << " " << max_val << std::endl;
    }

    return 0;
}