PAT|1099. Build A Binary Search Tree

先中序遍历然后层序遍历。

#include<iostream>
#include<stdio.h>
#include<vector>
#include<algorithm>
#include<stack>
#include<queue>
using namespace std;
struct node
{
    int val;
    int index;
    int left;
    int right;
};

bool cmp(int a,int b)
{
    return a < b;
}
int main()
{
    //该树的中序遍历结果是个递增的数组
    //在把树中序遍历的同时把排好序的数组一个一个插入就行了
    int n;
    while (scanf("%d",&n)!=EOF)
    {
        vector<node>tree(n);
        vector<int>num(n);
        for (int i = 0; i < n; i++)
        {
            tree[i].index = i;
            scanf("%d%d", &tree[i].left, &tree[i].right);
        }

        for (int i = 0; i < n; i++)
            scanf("%d", &num[i]);

        sort(num.begin(), num.end(), cmp);

        stack<node>s;
        int x = 0;
        int j = 0;
        while (x!=-1||!s.empty())
        {
            while (x != -1)
            {//左孩子入栈
                s.push(tree[x]);
                x = tree[x].left;
            }
            if (!s.empty())
            {
                int v = s.top().index;
                s.pop();
                tree[v].val = num[j++];
                x = tree[v].right;
            }
        }
        queue<int>q;
        printf("%d", tree[0].val);
        if (tree[0].left != -1)q.push(tree[0].left);
        if (tree[0].right != -1)q.push(tree[0].right);
        while (!q.empty())
        {
            int w = q.front();
            q.pop();
            printf(" %d", tree[w].val);
            if (tree[w].left != -1)q.push(tree[w].left);
            if (tree[w].right != -1)q.push(tree[w].right);
        }
        printf("\n");
    }
    return 0;
}