LeetCode 1. Two Sum 找到两数字求和索引集合

 https://leetcode.com/problems/two-sum/description/

第一种方法  遍历查找

//
//  main.m
//  HFCDemo
//
//  Created by HF on 2018/9/5.
//  Copyright © 2018年 HF. All rights reserved.
//

#import <Foundation/Foundation.h>

/**
 * Note: The returned array must be malloced, assume caller calls free().
 * int *array = (int *)malloc(sizeof(int) * 2);
 */
int* twoSum(int* nums, int numsSize, int target) {
    int oneIndex = 0;
    int twoIndex = 0;
    for (int i = 0;i < numsSize; i ++) {
        int one = nums[i];
        int two = target - one;
        for (int j = 0; j < numsSize; j ++) {
            if (j > i && nums[j] == two) {
                oneIndex = i;
                twoIndex = j;
                break;
            }
        }
    }
    //要求必须动态分配空间数组
    int *array = (int *)malloc(sizeof(int) * 2);
    array[0] = oneIndex;
    array[1] = twoIndex;
    return array;
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        NSLog(@"Hello, World!
");
        int numSize = 4;
        int nums[4] = {2, 7, 11, 15};
        int target = 9;
        int *array = twoSum(nums, numSize, target);
        printf("%d %d
",array[0],array[1]);
        free(array);
    }
    return 0;
}

第二种：哈希

待完成