每日一题||二叉树练习

Posted 2021-08-09 一只小跃跃

P1305：新二叉树

程序代码：

#include<iostream>using namespace std;struct Node{ char left; char right;}tree[1000];void dfs(char root){ cout<<root; if(tree[root].left!='*'){ dfs(tree[root].left);//左儿子做根继续  } if(tree[root].right!='*'){ dfs(tree[root].right);//右儿子做根继续  } }int main(){ int n; char temp,root; cin>>n; //第一步：构建树  for(int i=1;i<=n;i++){ cin>>temp; if(i==1){ root=temp; } cin>>tree[temp].left>>tree[temp].right; } //第二步：遍历树 dfs(root);  return 0;}

P4913:二叉树深度

程序代码：

#include<iostream>using namespace std;const int N=1e6+5;struct Node{ int left; int right;}tree[N];int count;void dfs(int root,int step){//前序遍历向下搜索  if(root==0){ return ; } count=max(count,step); dfs(tree[root].left,step+1);  dfs(tree[root].right,step+1);}int main(){ int n; cin>>n; //第一步：构建树  for(int i=1;i<=n;i++){ cin>>tree[i].left>>tree[i].right; } //第二步：遍历树 dfs(1,1); cout<<count;  return 0;}

P1030：求先序排列

程序代码：方式一

#include<iostream>#include<cstdlib>#include<cstring>using namespace std;
//使用指针接收两个字符串char *in=(char*)malloc(sizeof(char));//指向这个空间的地址char *post=(char*)malloc(sizeof(char)); struct Node{ char data; Node *left,*right;};
Node* build(int post_l,int post_r,int in_l,int in_r){ if(post_l>post_r){ return NULL; } Node *root=new Node; root->data=post[post_r];//后续遍历最后一个就是根  int k; for( k=in_l;k<in_r;k++){ if(in[k]==post[post_r]){ break; } } //前序遍历：1 2 3 4 5 6 7 //中序遍历：4 3 5 2 6 1 7 //后续遍历：4 5 3 6 2 7 1  int num=k-in_l; //中序遍历特点：根的左边是左子树，根的右边是右子树 root->left=build(post_l,post_l+num-1,in_l,k);  //后序遍历特点： root->right=build(post_l+num,post_r-1,k+1,in_r);  return root;}//前序遍历函数 void pre_order(Node *root){ if(root==NULL){ return ; } cout<<root->data; pre_order(root->left); pre_order(root->right);}int main(){ cin>>in>>post; // scanf("%s",in);// scanf("%s",post); int len=strlen(in); //创造一棵树  Node *root=build(0,len-1,0,len-1); pre_order(root);//前序遍历  return 0;}

程序代码：方式二

#include<iostream>#include<cstring>#include<cstdlib>using namespace std;struct Node{ char data; Node *left,*right;};Node* build(char* in,char* post,int length){ if(length==0){ return NULL; } Node * root=new Node; root->data=*(post+length-1); int k=0; for(;k<length;k++){ if(in[k]==root->data){ break; } } cout<<root->data; root->left=build(in,post,k); root->right=build(in+k+1,post+k,length-(k+1)); return root;}int main(){ char *in=(char*)malloc(sizeof(char));//动态开辟空间  char *post=(char*)malloc(sizeof(char));; cin>>in>>pre; int len=strlen(in); build(in,post,len); return 0;}

P1827:美国血统

程序代码：

#include<iostream>#include<cstring>#include<cstdlib>using namespace std;struct Node{ char data; Node *left,*right;};Node* build(char* in,char* pre,int length){ if(length==0){ return NULL; } Node * root=new Node; root->data=*pre; int k=0; for(;k<length;k++){ if(in[k]==*pre){ break; } } root->left=build(in,pre+1,k); root->right=build(in+k+1,pre+k+1,length-(k+1)); cout<<root->data; return root;}int main(){ char *in=(char*)malloc(sizeof(char));//动态开辟空间  char *pre=(char*)malloc(sizeof(char));; cin>>in>>pre; int len=strlen(in); build(in,pre,len); return 0;}