TIOJ 1108 樹的三兄弟

#include <cstdio>
#include <cstdlib>
#include <vector>
#include <string.h>
using namespace std;

char pre[55], in[55];
vector<char> post;

int search(char* s, char c){
    for (int i = 0; i < strlen(s); ++i)
        if(s[i] == c)
            return i;

    return -1;
}

void FindPost(char* _in, char* _pre, int len){
    int root = search(_in, _pre[0]);

    if(root > 0)
        FindPost(_in, _pre + 1, root);

    if(root < len - 1)
        FindPost(_in + root + 1, _pre + root + 1, len - root - 1);

    post.push_back(_pre[0]);
}

int main(){
    while(scanf("%s", pre) != EOF){
        scanf("%s", in);

        post.clear();
        FindPost(in, pre, strlen(in));

        for (int i = 0; i < post.size(); ++i)
            printf("%c", post[i]);
        printf("\n");
    }
}