题解 | #二叉排序树#

#include <iostream>
using namespace std;
struct TreeNode{
    int data;
    TreeNode * leftchild;
    TreeNode * rightchild;
};
void insertBTS(TreeNode *&root, int data){
    TreeNode *pnode = new TreeNode;
    pnode->data = data;
    pnode->leftchild = NULL;
    pnode->rightchild = NULL;

    if(root == NULL){
        root = pnode;
        printf("-1\n");

    }
    else{
        TreeNode *pPre = root;
        // TreeNode *Pcur;
        while(true){
            if(data > pPre->data && pPre->rightchild ==NULL){
            // Pcur = root->rightchild;
            pPre->rightchild = pnode;
            printf("%d\n",pPre->data);
            break;
        }
        else if(data < pPre->data && pPre->leftchild ==NULL){
            pPre->leftchild = pnode;
            printf("%d\n",pPre->data);
            break;
        }
        else if(data < pPre->data){
            pPre = pPre->leftchild;
        }
        else if(data > pPre->data){
            pPre = pPre->rightchild;
        }
        }
        
    }
}
int main() {
    TreeNode *ans = NULL;
    int n;
    while (scanf("%d",&n)!=EOF) { // 注意 while 处理多个 case
        for(int i=0;i<n;++i){
            int x;
            scanf("%d",&x);
            insertBTS(ans,x);
        }
    }
}
// 64 位输出请用 printf("%lld")