hdu 1701 (Binary Tree Traversals)（二叉树前序中序推后序）

#include <stdio.h>  
#include <string.h>  
int n;
int a[1000], b[1000], c[1000]; 


void build( int len, int s1, int s2, int s )  
{  
    int p;  
    int i;  
    if(len<=0)  
        return;  
    else  
    {  
        for(i=s2; i<s2+len; i++ )  
        {  
            if(b[i]==a[s1])  
            {  
                p = i;  
				break;
            }  
        }  
		 c[s+len-1] = a[s1]; 

        build(p, s1+1, s2, s );  //左
        build(len-p-1, s1+p+1, s2+p+1, s+p);  //右
        
    }  
}  
int main()  
{  
     int i, j;
     while(scanf("%d", &n)!=EOF)
	 {
		 for(i=0; i<n; i++)
		 {
			 scanf("%d", &a[i] );
		 }
		 for(i=0; i<n; i++)
		 {
			 scanf("%d", &b[i] );
		 }
		 build(n, 0, 0, 0);
	
	    for(i=0; i<n; i++)
		{
		   printf("*%d ", c[i] );
		}
	 }
	
    
	return 0;
}   
  

#include <stdio.h>  
#include <string.h>  
void build(int len, int *s1, int *s2, int *s)  
{  
    int p;  
    int i;  
    if(len<=0)  
        return;  
  
    else  
    {  
        for(i=0; i<len; i++)  
        {  
            if(s2[i]==s1[0])  
            {  
                p = i;  
            }  
        }  
        build(p, s1+1, s2, s);  
        build(len-p-1, s1+p+1, s2+p+1, s+p);  
        s[len-1] = s1[0];  
    }  
}  
int main()  
{  
	int i;

    int s1[1000], s2[1000], s3[1000];  
    int n;
	while(scanf("%d", &n)!=EOF)
	{
		for(i=0; i<n; i++)
		 {
			 scanf("%d", &s1[i] );
		 }
		 for(i=0; i<n; i++)
		 {
			 scanf("%d", &s2[i] );
		 }
		 build(n, s1, s2, s3 );
		 for(i=0; i<n; i++)
		 {
			 printf("%d%c", s3[i], i==n-1?‘\n‘:‘ ‘ );
		 }
	}
  
	return 0;
}