1102. Invert a Binary Tree (25)

    唯一注意一点，就是根结点这里并未给出，需要自己根据输入判断出来。

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>

using namespace std;

#define INF (~(1<<31))

struct Node{
int id, left, right;

Node(){}
Node(int i, int l, int r) : id(i), left(l), right(r){}
};

vector<Node> nodes;
vector<int> level;
vector<int> inorder;

void invert(int root){
if(root == -1) return;

swap(nodes[root].left, nodes[root].right);
invert(nodes[root].left);
invert(nodes[root].right);
}

void inorderTranversal(int root){
if(root == -1) return;

inorderTranversal(nodes[root].left);
inorder.push_back(root);
inorderTranversal(nodes[root].right);
}

int main(){
int n;
cin >> n;

vector<int> father(n, -1);
nodes.resize(n);

for(int i = 0; i < n; ++i){
char l, r;
cin >> l >> r;
int left = -1, right = -1;

if(l != '-') left = l - '0';
if(r != '-') right = r - '0';

nodes[i] = Node(i, left, right);

if(left != -1) father[left] = i;
if(right != -1) father[right] = i;
}

int root = find_if(begin(father), end(father), [](int val){ return val == -1; }) - begin(father);

invert(root);

queue<int> Q;
Q.push(root);

while(!Q.empty()){
int r = Q.front(); Q.pop();

level.push_back(r);
if(nodes[r].left != -1) Q.push(nodes[r].left);
if(nodes[r].right != -1) Q.push(nodes[r].right);
}

inorderTranversal(root);

for(size_t i = 0; i < level.size(); ++i){
if(i) printf(" ");
printf("%d", level[i]);
}

printf("\n");
for(size_t i = 0; i < inorder.size(); ++i){
if(i) printf(" ");
printf("%d", inorder[i]);
}

return 0;
}