括号生成（回溯法）

/*
有效的括号--回溯法。
*/
#include<stdio.h>
#include<malloc.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#include <iostream>
void generate(int left,int right,int n,char *str,int index,char** rs,int *returnSize){
    if(left==n&&right==n){
        rs[(*returnSize)]=(char*)malloc(sizeof(char)*(2*n+1));
        str[index]='';
        strcpy(rs[(*returnSize)],str);
        (*returnSize)++;
        printf("%s ",str);
        return;
    }
    if(left<n){
        str[index]='(';
        generate(left+1,right,n,str,index+1,rs,returnSize);
    }
    if(right<n&&right<left){
        str[index]=')';
        generate(left,right+1,n,str,index+1,rs,returnSize);
    }
}
char ** generateParenthesis(int n, int* returnSize){
    char *str=(char*)malloc(sizeof(char)*(2*n+1));
    char **rs=(char**)malloc(sizeof(char*)*2500);
    (*returnSize)=0;
    generate(0,0,n,str,0,rs,returnSize);
}

int main()
{
    char **rs=(char**)malloc(sizeof(char*)*2500);
    int *returnSize=(int*)malloc(sizeof(int)*(7));
    rs=generateParenthesis(3,returnSize);
    return 0;
}