const int maxn=105;char s1[maxn],s2[maxn],s[maxn];//s1為先序遍歷結果，s2為中序遍歷結果，s為后續遍歷結果void build(int n,char *s1,char *s2,char *s) //n為字符串長度{    if(n<=0) return ;    int p = strchr(s2,s1[0])-s2;    build(p,s1+1,s2,s);    build(n-1-p,s1+p+1,s2+p+1,s+p);    s[n-1] = s1[0];}/*在main函數里加句s[n]='/0';*/