77. 组合c

/**
 * 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[30];

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

int** combine(int n, int k, int* returnSize, int** returnColumnSizes) {
    *returnSize=0;
    int* column=(int*)malloc(sizeof(int)*200000);
    int** array=(int**)malloc(sizeof(int*)*200000);
    dfs(array,column,n,k,returnSize,1,0);
    *returnColumnSizes=column;
    return array;
}