添加 0015.三数之和.md C语言版本

This commit is contained in:
Guanzhong Pan
2021-11-29 11:56:50 +00:00
parent 10357ec645
commit d1d3b28341

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@ -435,5 +435,79 @@ func threeSum(_ nums: [Int]) -> [[Int]] {
}
```
C:
```C
//qsort辅助cmp函数
int cmp(const void* ptr1, const void* ptr2) {
return *((int*)ptr1) > *((int*)ptr2);
}
int** threeSum(int* nums, int numsSize, int* returnSize, int** returnColumnSizes) {
//开辟ans数组空间
int **ans = (int**)malloc(sizeof(int*) * 18000);
int ansTop = 0;
//若传入nums数组大小小于3则需要返回数组大小为0
if(numsSize < 3) {
*returnSize = 0;
return ans;
}
//对nums数组进行排序
qsort(nums, numsSize, sizeof(int), cmp);
int i;
//用for循环遍历数组结束条件为i < numsSize - 2(因为要预留左右指针的位置)
for(i = 0; i < numsSize - 2; i++) {
//若当前i指向元素>0则代表left和right以及i的和大于0。直接break
if(nums[i] > 0)
break;
//去重i > 0 && nums[i] == nums[i-1]
if(i > 0 && nums[i] == nums[i-1])
continue;
//定义左指针和右指针
int left = i + 1;
int right = numsSize - 1;
//当右指针比左指针大时进行循环
while(right > left) {
//求出三数之和
int sum = nums[right] + nums[left] + nums[i];
//若和小于0则左指针+1因为左指针右边的数比当前所指元素大
if(sum < 0)
left++;
//若和大于0则将右指针-1
else if(sum > 0)
right--;
//若和等于0
else {
//开辟一个大小为3的数组空间存入nums[i], nums[left]和nums[right]
int* arr = (int*)malloc(sizeof(int) * 3);
arr[0] = nums[i];
arr[1] = nums[left];
arr[2] = nums[right];
//将开辟数组存入ans中
ans[ansTop++] = arr;
//去重
while(right > left && nums[right] == nums[right - 1])
right--;
while(left < right && nums[left] == nums[left + 1])
left++;
//更新左右指针
left++;
right--;
}
}
}
//设定返回的数组大小
*returnSize = ansTop;
*returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
int z;
for(z = 0; z < ansTop; z++) {
(*returnColumnSizes)[z] = 3;
}
return ans;
}
```
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<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>