Tree Recovery

#include<stdio.h>
#include<string.h>
void build(int n,char*s1,char*s2)
{
    if(n<=0)return ;
    int p=strchr(s2,s1[0])-s2;///p表示左结点的个数
    build(p,s1+1,s2);///查找左结点
    build(n-p-1,s1+p+1,s2+p+1);///查找右结点
    printf("%c",s1[0]);///输出每次递归的结点值
}
int main()
{
    char s1[30],s2[30];
    memset(s1,0,sizeof(s1));
    memset(s2,0,sizeof(s2));
    while(scanf("%s %s",s1,s2)!=EOF)
    {
        int n=strlen(s1);
        build(n,s1,s2);
        printf("\n");
    }
    return 0;
}