C实现 LeetCode->3Sum

Given an array  S of  n integers, are there elements  a,  b,  c in  S such that  a +  b +  c = 0? Find all unique triplets in the array which gives the sum of zero.

1:给定一个 整形数组S 里面的元素 满足 a+b+C ＝0 ；

2:满足a<= b <= c 排序

//
//  3Sum.c
//  Algorithms
//
//  Created by TTc on 15/6/12.
//  Copyright (c) 2015年 TTc. All rights reserved.
//

#include "3Sum.h"
#include <stdlib.h>
#include <string.h>
/**
 *
 　　三元素(a,b,c)必须排序。(a≤b≤c)
 　　解集必须不包含重复的三元素。
 */


static int
cmp(const int*a,const int *b){
    return *a - *b;
}
/**
 * Return an array of arrays of size *returnSize.
 * Note: The returned array must be malloced, assume caller calls free().
 */
int**
threeSum(int* nums, int numsSize, int* returnSize){
    if (numsSize <= 0) return NULL;
    int total = 64;
    int size = 0;
    int i,start,end,sum;
    int ** result = (int **)malloc(sizeof(int *) * total);

    for(i = 0 ;i< total; i++){
        result[i] = (int *)malloc(sizeof(int)* 3);
    }
    qsort(nums, numsSize, sizeof(int), (int(*)(const void *,const void *))cmp);
    
    for(i = 0; i < numsSize-2; ++i){
        if(i > 0 && nums[i] == nums[i-1]){
            continue;
        }
        start = i + 1;
        end = numsSize - 1;
        while(start < end){
            sum = nums[i] + nums[start] + nums[end];
            if(sum == 0){
                if(size > 0 && result[size-1][0] == nums[i] &&
                   result[size-1][1] == nums[start] && result[size-1][2] == nums[end]){
                    ++start;
                    --end;
                    continue;
                }
                result[size][0] = nums[i];
                result[size][1] = nums[start];
                result[size][2] = nums[end];
                size++;
                
                if(size == total){
                    total <<= 1;
                    int t;
                    result = (int **)realloc(result,sizeof(int *) * total);
                    for(t = size; t < total; ++t)
                        result[t] = (int *)malloc(sizeof(int) * 3);
                }
                ++start;
                --end;
            } else if(sum > 0){
                --end;
            }else{
                ++start;
            }
        }
    }
    
    *returnSize = size;
    return result;
}


void
test_3Sum(){
    int nums[10] = {-1, 0 ,1 ,2 ,-1, -4};
    int * returnSize = NULL;
    returnSize = malloc(sizeof(int));
    int ** result = threeSum(nums, 6, returnSize);
    printf("returnSize===%d \n",*returnSize);
    
    for (int j = 0; j < *returnSize; j++) {
        for (int i = 0 ; i < 3; i++) {
            printf("result[%d][%d]===%d \n",j,i,result[0][i]);
        }
    }
}