Tree Recovery UVA - 536

根据树的前序和中序遍历的结果得到它后序遍历的结果

注意递归函数的写法，控制好递归的边界就行了

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<string>
#include<vector>
#include<algorithm>
#include<assert.h>
using namespace std;
string pre, in;
void build(int lx, int rx, int ly, int ry)
{
	if (lx > rx || ly > ry) return;
	char root = pre[lx];
	int i;
	for (i = ly; i <= ry; i++) if (in[i] == root) break;
	int cnt = i - ly;
	build(lx + 1, lx + cnt, ly, i - 1);
	build(lx + cnt + 1, rx, i + 1, ry);
	cout << root;
}
int main()
{
	while (cin >> pre >> in)
	{
		int lena = pre.length();
		int lenb = in.length();
		build(0, lena - 1, 0, lenb - 1);
		cout << endl;
	}
	//system("pause");
}