二叉树 由中序遍历和前序遍历推后序遍历

根据后序遍历’=‘左子树的后序遍历’+‘右子树的后序遍历’+‘根节点递归求解即可

char pre[maxn], in[maxn], post[maxn];

void Post(char* _pre, char* _in, int _len, int _root) {
	if (_len <= 0) return;
	int i = 0;
	while (_in[i] != _pre[0]) ++i;
	Post(_pre + 1, _in, i, _root - (_len - i - 1) - 1);
	Post(_pre + i + 1, _in + i + 1, _len - i - 1, _root - 1);
	post[_root] = _pre[0];
}

int main() {
	//std::ios::sync_with_stdio(0);
	//std::cin.tie(0);
#ifdef NIGHT_13
	freopen("in.txt", "r", stdin);
	//freopen("myout.txt", "w", stdout);
#endif
	scanf("%s%s", pre, in);
	int len = strlen(in);
	Post(pre, in, len, len - 1);
	printf("%s\n", post);
	return 0;
}