78. 子集c

leetcode官方解法实在是太绝了！！二刷的时候一定用上！

/**
 * Return an array of arrays of size *returnSize.
 * The sizes of the arrays are returned as *returnColumnSizes array.
 * Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
 */
int temp[40];

void dfs(int* nums,int numsSize,int** array,int* returnSize,int* column,int index,int count){
    if(index>numsSize) return;
    column[*returnSize]=count;
    array[*returnSize]=(int*)malloc(sizeof(int)*(count+1));
    for(int i=0;i<count;i++) array[*returnSize][i]=temp[i];
    (*returnSize)++;
    for(int i=index;i<numsSize;i++){
        temp[count]=nums[i];
        dfs(nums,numsSize,array,returnSize,column,i+1,count+1);
        temp[count]=0;
    }
}

int** subsets(int* nums, int numsSize, int* returnSize, int** returnColumnSizes) {
    *returnSize=0;
    int* column=(int*)malloc(sizeof(int)*3000);
    int** array=(int**)malloc(sizeof(int*)*3000);
    dfs(nums,numsSize,array,returnSize,column,0,0);
    *returnColumnSizes=column;
    return array;
}

结果：