卡特兰数—以leetcode22括号生成为例（笔记）

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
void bracket(int left,int right,int n,char arr[],char c,char **returns,int *returnSize)
{
    if(left == 0 && right == 0)
    {
        arr[left+right] = c;
    }
    else{
        arr[left+right-1] = c;
    }
    printf("%c",c);
    if(left < right || left > n || right > n)
        return;
    if(left == n && right == n)
    {
        returns[(*returnSize)] = (char *)calloc((2*n+1),sizeof(char));
        // printf("%s",arr);
        strcpy(returns[(*returnSize)],arr);
        (*returnSize)++;
        return;
    }
    bracket(left+1,right,n,arr,'(',returns,returnSize);
    bracket(left,right+1,n,arr,')',returns,returnSize);
    return;
}
// void copy(char *dest,char *src)
// {
  // int i,j=0;
  // for(i=0;i<strlen(src);i++)
  // {
        // dest[j]=src[i];
  // }
  // printf("%s\n",dest);
// }
char ** generateParenthesis(int n, int* returnSize){
    *returnSize = 0;
    printf("@");
    char ** returns = (char **)malloc(sizeof(char *)*1500);
    printf("1");
    char * arr = (char *)calloc((2*n+1),sizeof(char));
    bracket(0,0,n,arr,'(',returns,returnSize);
    return returns;
}