洛谷-----P1030 求先序排列

一、題目分析

        題目連接：https://www.luogu.org/problemnew/show/P1030。其實這道題就是一道根據樹的中序和後序遍從來求先序遍歷。在leetcode以前作過，能夠參考這裏。代碼稍微改改，加上輸入輸出便可。

二、代碼

#include<iostream>
#include<string>
using namespace std;
void dfs(string &mid, string &last){
	if (mid.size() == 0||last.size()==0) return;
	string temp_mid_left,temp_mid_right, temp_last_left,temp_last_right;
	int target = 0;
	for (int i = 0; i < mid.size(); ++i){
		if (mid[i] == last[last.size() - 1]){
			target = i;
			break;
		}
	}
	cout << last[last.size() - 1];
	for (int i = 0; i < target; ++i){
		temp_mid_left.push_back(mid[i]);
		temp_last_left.push_back(last[i]);
	}
	for (int i = target + 1; i < mid.size(); ++i){
		temp_mid_right.push_back(mid[i]);
		temp_last_right.push_back(last[i-1]);
	}
	if (temp_mid_left.size() != 0){
		dfs(temp_mid_left, temp_last_left);
	}
	if (temp_mid_right.size() != 0){
		dfs(temp_mid_right, temp_last_right);
	}
}
int main(){
	string a, b;
	cin >> a ;
	cin >> b ;
	dfs(a, b);	
	return 0;
}