二叉树重建 （ 根据中序序列和前序序列获取后序序列）

void build(int n, char*s1, char*s2, char*s) {
    if (n<=0) return;
    int p = strchr(s2, s1[0]) - s2; 
    build(p, s1 + 1, s2, s);
    build(n-p-1, s1 + p + 1, s2 + p + 1, s + p);
    s[n-1] = s1[0];
}

int main () {
    char s1[100], s2[100];

    while(scanf("%s%s", s1, s2) == 2) {
        int n = strlen(s1);
        char ans[100] = {0};
        build(n, s1, s2, ans);
        ans[n] = '\0';
        printf("%s\n", ans);
    }

    system("PAUSE");
    return 0;
}