蓝桥杯 PREV-11 横向打印二叉树

题目链接：

PREV-11 横向打印二叉树

思路：

首先递归建立二叉搜索树；
用字符串数组保存横向打印的二叉树，然后按层递归打印，注意打印的细节即可；

代码：

#include<bits/stdc++.h>

using namespace std;

string s[205];
const int maxn = 1e4 + 5;
int lf[maxn], rt[maxn], ln[maxn], rn[maxn];
inline void add(int x, int u) {
	if(x < u) {
		++ln[u];
		if(lf[u] == 0) lf[u] = x;
		else add(x, lf[u]);
	}else {
		++rn[u];
		if(rt[u] == 0) rt[u] = x;
		else add(x, rt[u]);	
	}
}
#define len(n) ((int)log10(n) + 1)
inline string itos(int n) {
	string str = "";
	while(n) str = (char)(n % 10 + '0') + str, n /= 10;
	return str;	
}
void dfs(int u, int pos) {
	s[pos] += itos(u);
	if(ln[u] || rn[u]) s[pos] += "-|";
	string str = ".";
	for(int i = len(u); i--;) str += ".";
	int lp = pos + 1 + rn[lf[u]], rp = pos - 1 - ln[rt[u]];
	for(int i = 1; i <= rn[u]; i++) {
		s[pos - i] += str;
		s[pos - i] += pos - i >= rp ? "|" : ".";
		s[pos - i] += pos - i == rp ? "-" : ".";
	}
	for(int i = 1; i <= ln[u]; i++) {
		s[pos + i] += str;
		s[pos + i] += pos + i <= lp ? "|" : ".";
		s[pos + i] += pos + i == lp ? "-" : ".";
	}
	if(lf[u]) dfs(lf[u], lp);
	if(rt[u]) dfs(rt[u], rp);
}
int main() {
#ifdef MyTest
	freopen("Sakura.txt", "r", stdin);
#endif
	int v, root;
	scanf("%d", &root);
	while(~scanf("%d", &v)) add(v, root);
	dfs(root, 100);
	for(int i = 100 - rn[root]; i <= 100 + ln[root]; i++) 
		cout << s[i] << '\n';
	return 0;	
}