【leetcode】22. 括号生成

• void recursion(char** arr,char* s,int cur,int cnt,int num,int n,int* returnSize){
      if (cur == n*2){
          arr[(*returnSize)] = (char*)calloc(n*2 + 1, sizeof(char));
          strcat(arr[(*returnSize)++], s);
          return;
      }
      for (int i = 0; i < 2; i++){
          if(num==0 && i==1 || num==n && i==0 || cnt==n && i==0 || cnt==0 && i==1) 
              continue;        
          s[cur] = (i)?')' :'(';
          recursion(arr, s, cur+1, (i)?cnt-1 :cnt+1, (i==0)?num+1 :num, n, returnSize);
          s[cur] = '';
      }
  }
  char ** generateParenthesis(int n, int* returnSize){    
      *returnSize = 0;
      char** arr = (char**)calloc(10000, sizeof(char*));
      char* s = (char*)calloc(n*2+1, sizeof(char));
      if (n==0) return NULL;
      recursion(arr,s, 0, 0, 0, n,returnSize);
      return arr;
  }