Leetcode: Generate Parentheses

#include <stdio.h>
#include <stdlib.h>

/**
 * Return an array of size *returnSize.
 * Note: The returned array must be malloced, assume caller calls free().
 */
char** generateParenthesis(int n, int* returnSize) {

  char ** result = NULL;
  if(n == 1) {
    /* if n == 1 */
    result = (char **) malloc(sizeof(char *) * 1);
    result[0] = (char *) malloc(sizeof(char) * 2 * n);
    result[0][0] = '(';
    result[0][1] = ')';
    *returnSize = 1;
  } else {
    /* if n > 1 */
    int subSize = 0;
    char ** subResult = generateParenthesis(n-1, &subSize);
    *returnSize = subSize * 3 - 1;
    printf("returnSize = %d
", *returnSize);
    result = (char **) malloc(sizeof(char *) * (*returnSize));

    int i=0,j=0;
    for(i=0; i<subSize; i++) {
      result[i] = (char *) malloc(sizeof(char) * 2 * n);
      result[i][0] = '(';
      result[i][2*n-1] = ')';
      for(j=0; j<2*(n-1); j++) {
        result[i][j+1] = subResult[i][j];
      }
    }
    int m = subSize;
    for(i=0; i<subSize-1; i++) {
      result[i+m] = (char *) malloc(sizeof(char) * 2 * n);
      result[i+m][2*n-2] = '(';
      result[i+m][2*n-1] = ')';
      for(j=0; j<2*(n-1); j++) {
        result[i+m][j] = subResult[i][j];
      }
    }

    m = subSize + subSize - 1;

    for(i=0; i<subSize-1; i++) {
      result[i+m] = (char *) malloc(sizeof(char) * 2 *n);
      result[i+m][0] = '(';
      result[i+m][1] = ')';
      for(j=0; j<2*(n-1); j++) {
        result[i+m][j+2] = subResult[i][j];
      }
    }

    result[*returnSize-1] = (char *) malloc(sizeof(char) * 2 * n);
    result[*returnSize-1][0] = '(';
    result[*returnSize-1][1] = ')';
    for(j=0; j<2*(n-1); j++) {
        result[*returnSize-1][j+2] = subResult[i][j];
    }

    for(i=0; i<subSize; i++) {
      free(subResult[i]);
    }
    free(subResult);
  }

  char ** append = (char **) malloc(sizeof(char *) * (*returnSize));
  int k=0,j=0;
  for(k=0; k<(*returnSize); k++) {
    append[k] = (char *) malloc(sizeof(char) * (2 * n+1));
    for(j=0; j< 2*n; j++) {
      append[k][j] = result[k][j];
    }
    append[k][j+1] = '';
  }
  return append;
}

void print(char ** result, int n, int size) {
  int i=0, j=0;
  for(i=0; i<size; i++) {
    for(j=0; j<2*n; j++) {
      printf("%c", result[i][j]);
    }
    printf("
");
  }
  printf("===================
");
}

int main(int argc, char * argv[]) {
  int size = 0, n = 10;
  char ** result = generateParenthesis(n, &size);
  printf("generate success...
");
  print(result, n, size);
  printf("hello
");
  return 0;
}

改进版，欣赏一下鄙人的黑暗代码：

#include <stdio.h>
#include <stdlib.h>

struct Node {
  char * s;
  struct Node * next;
  int num;
};

void generate(int leftNum, int rightNum, char * s, struct Node * result) {

  if(leftNum == 0 && rightNum == 0) {
    struct Node * p = result;
    while(p->next != NULL) p = p->next;
    p->next = (struct Node *) malloc(sizeof(struct Node));
    p = p->next;
    p->next = NULL;
    p->s = s;
  }

  if(leftNum > 0) {
    char * item = (char *) malloc(sizeof(char) * (result->num * 2 + 1));
    int i=0;
    for(i=0; i<result->num*2 + 1; i++) {
      item[i] = s[i];
    }
    for(i=0; i<result->num*2 + 1; i++) {
      if(s[i] == '') break;
    }
    item[i] = '(';
    item[result->num*2] = '';

    generate(leftNum-1, rightNum, item, result);
  }

  if(rightNum > 0 && leftNum < rightNum) {
    char * item = (char *) malloc(sizeof(char) * (result->num * 2 + 1));
    int i=0;
    for(i=0; i<result->num*2 + 1; i++) {
      item[i] = s[i];
    }
    for(i=0; i<result->num*2 + 1; i++) {
      if(s[i] == '') break;
    }
    item[i] = ')';
    item[result->num*2] = '';

    generate(leftNum, rightNum-1, item, result);
  }
}



/**
 * Return an array of size *returnSize.
 * Note: The returned array must be malloced, assume caller calls free().
 */
char** generateParenthesis(int n, int* returnSize) {

  struct Node link_list_result;
  link_list_result.num = n;
  link_list_result.next = NULL;
  char * s = (char *) malloc(sizeof(char) * (2*n + 1));
  int i=0;
  for(i=0; i<2*n+1; i++) s[i] = '';
  struct Node * p = link_list_result.next;
  printf("1111111111
");
  generate(n, n, s, &link_list_result);
  printf("22222222222
");
  p=link_list_result.next;
  while(p != NULL) {
    printf("---> %s
", p->s);
    p = p->next;
  }
  int total = 0;
  p=link_list_result.next;
  while(p != NULL) {
    total++;
    p = p->next;
  }
  *returnSize = total;
  char ** result = (char **) malloc(sizeof(char *) * total);
  p = link_list_result.next;
  i=0;
  while(p != NULL) {
    printf("set...%s
", p->s);
    result[i++] = p->s;
    p = p->next;
  }

  printf("returnSize = %d", *returnSize);

  for(i=0; i<*returnSize; i++) {
    printf("------> %s
", result[i]);
  }
  return result;

}

void print(char ** result, int n, int size) {
  int i=0, j=0;
  for(i=0; i<size; i++) {
    for(j=0; j<2*n; j++) {
      printf("%c", result[i][j]);
    }
    printf("
");
  }
  printf("===================
");
}

int main(int argc, char * argv[]) {
  int size = 0, n = 3;;
  char ** result = generateParenthesis(n, &size);
  printf("generate success...
");
  print(result, n, size);
  printf("hello
");
  return 0;
}

 

两种方法的结果内容一样，但是次序会有差别，leetcode只认第二种。