PAT 1066. Root of AVL Tree

来源：互联网发布：rayban眼镜知乎编辑：程序博客网时间：2024/05/20 11:26

题目：http://pat.zju.edu.cn/contests/pat-a-practise/1066

题解：

考察数据结构;AVL树。

重点就是四种情况的识别和处理。

代码：

#include<cstdio>#include<cstring>#include<cmath>#include<string>#include<vector>#include<map>#include<set>#include<stack>#include<queue>#include<algorithm>using namespace std;#define INF 0x6fffffff#define MAX 25struct point{    int value;    int left;    int right;    int heigh;}node[MAX];int idx;int getHeight(int root){    if(root==-1) return -1;    return node[root].heigh;}int rotateLL(int root){    int child=node[root].left;    node[root].left=node[child].right;//root的左孩纸变成原左孩纸的右孩纸    node[child].right=root;//原root左孩纸的右孩纸变成root    node[root].heigh=max(getHeight(node[root].left),getHeight(node[root].right))+1;    node[child].heigh=max(getHeight(node[child].left),getHeight(node[child].right))+1;    return child;}int rotateRR(int root){    int child=node[root].right;    node[root].right=node[child].left;//root的右孩纸变成原右孩纸的左孩纸    node[child].left=root;//原root右孩纸的左孩纸变成root    node[root].heigh=max(getHeight(node[root].left),getHeight(node[root].right))+1;    node[child].heigh=max(getHeight(node[child].left),getHeight(node[child].right))+1;    return child;}int rotateLR(int root){    int child=node[root].left;    node[root].left=rotateRR(child);    return rotateLL(root);}int rotateRL(int root){    int child=node[root].right;    node[root].right=rotateLL(child);    return rotateRR(root);}bool isBalance(int root){    return abs(getHeight(node[root].left)-getHeight(node[root].right))<2;}int insertNode(int root,int x)//插入新结点{    if(root!=-1)    {        if(x>node[root].value)//右        {            node[root].right=insertNode(node[root].right,x);            if(!isBalance(root))            {                if(x>node[node[root].right].value)//右右                    root=rotateRR(root);                else//右左                    root=rotateRL(root);            }        }        else        {            node[root].left=insertNode(node[root].left,x);            if(!isBalance(root))            {                if(x>node[node[root].left].value)//左右                    root=rotateLR(root);                else//左左                    root=rotateLL(root);            }        }    }    else    {        node[idx].value=x;        node[idx].left=node[idx].right=-1;        node[idx].heigh=0;        root=idx;        ++idx;    }    node[root].heigh=max(getHeight(node[root].left),getHeight(node[root].right))+1;    return root;}void dfs(int root){    if(root==-1) return;    if(node[root].left!=-1)    {        printf("%d left-> %d\n",node[root].value,node[node[root].left].value);        dfs(node[root].left);    }    if(node[root].right!=-1)    {        printf("%d right-> %d\n",node[root].value,node[node[root].right].value);        dfs(node[root].right);    }}int main(){    int n,x,root;    scanf("%d",&n);    idx=0;    root=-1;    for(int i=0;i<n;++i)    {        scanf("%d",&x);        root=insertNode(root,x);        //printf("start\n");//测试        //dfs(root);        //printf("\n");    }    //dfs(root);    printf("%d\n",node[root].value);    return 0;}

来源：http://blog.csdn.net/acm_ted/article/details/20855913

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