波兰表达式和逆波兰表达式

波兰表达式和逆波兰表达式分别是一颗二叉树的前序遍历和后序遍历。

方法一：递归

#include <iostream>
#include <string>
using namespace std;
struct Tree 
{
char value;
Tree *left;
Tree *right;
};
void solution_LRD(Tree *head)
{

if(head)
{
solution_LRD(head->left);
solution_LRD(head->right);
cout<<head->value;
}

}
void solution_DLR(Tree *head)
{
if (head)
{
cout<<head->value;
solution_LRD(head->left);
solution_LRD(head->right);
}
}
int main()
{
char arr[16]="(a+b)*c-(a+b)/e";
Tree tree[11];
tree[7].value=arr[7];
tree[7].left=&tree[5];
tree[7].right=&tree[13];


tree[5].value=arr[5];
tree[5].left=&tree[2];
tree[5].right=&tree[6];


tree[13].value=arr[13];
tree[13].left=&tree[10];
tree[13].right=&tree[14];


tree[2].value=arr[2];
tree[2].left=&tree[1];
tree[2].right=&tree[3];


tree[6].value=arr[6];
tree[6].left=NULL;
tree[6].right=NULL;

tree[10].value=arr[10];
tree[10].left=&tree[9];
tree[10].right=&tree[11];


tree[14].value=arr[14];
tree[14].left=NULL;
tree[14].right=NULL;


tree[1].value=arr[1];
tree[1].left=NULL;
tree[1].right=NULL;


tree[3].value=arr[3];
tree[3].left=NULL;
tree[3].right=NULL;


tree[9].value=arr[9];
tree[9].left=NULL;
tree[9].right=NULL;


tree[11].value=arr[11];
tree[11].left=NULL;
tree[11].right=NULL;


solution_DLR(&tree[7]);
cout<<endl;


solution_LRD(&tree[7]);
cout<<endl;
//solution_DLR(&tree[7]);
//cout<<endl;
return 0;
}