表达式二叉树的C++实现

#include <iostream>
#include <stack>
#include <string>
using namespace std;

int prior[1000]=...{0};
char oper[]=...{'(',')','+','-','*','/','^'};
int testcase;
string expr;
char tmpchr,c;


class Node...{
public:
    char oper;
    Node * left;
    Node * right;
    Node()...{left=right=NULL;};
    Node(char op)...{left=right=NULL;oper=op;}
};

stack<char>operStack;
stack<Node *>dataStack;

void generateTree(Node * &p,int idx)
...{
   
    tmpchr=expr[idx];
    while(!(operStack.top()=='#' && tmpchr=='#'))...{
        if(!prior[tmpchr])...{
            p=new Node(tmpchr);
            dataStack.push(p);
        }
        else ...{
            switch(tmpchr)...{
            case '(':
                operStack.push('(');
                break;
            case ')':
                c=operStack.top(); operStack.pop();
                while(c!='(')...{
                    p=new Node(c);
                    p->right=dataStack.top(); dataStack.pop();
                    p->left=dataStack.top(); dataStack.pop();
                    dataStack.push(p);
                    c=operStack.top(); operStack.pop();
                }
                break;
            default:
                while(operStack.size() && prior[operStack.top()]>prior[tmpchr])...{
                    p=new Node(operStack.top());
                    p->oper=operStack.top();
                    if(dataStack.size())...{p->right=dataStack.top(); dataStack.pop();}
                    if(dataStack.size())...{p->left=dataStack.top(); dataStack.pop();}
                    dataStack.push(p);
                    operStack.pop();
                }
                if(tmpchr!='#')operStack.push(tmpchr);
                break;
            }
        }
        if(tmpchr!='#')tmpchr=expr[++idx];
    }
    p=dataStack.top(); dataStack.pop();
}

inline void freeTree(Node * p)
...{
    if(p->left!=NULL)freeTree(p->left);
    if(p->right!=NULL)freeTree(p->right);
    delete(p);
}

void postOrderTraverse(Node * p)
...{
    if(p)...{
        postOrderTraverse(p->left);
        postOrderTraverse(p->right);
        cout<<p->oper;
    }
}

Node * tree;

int main()
...{
    cin>>testcase;
    for(int i=0;i<7;i++)prior[oper[i]]=i+2;
    prior['#']=1;
    while(testcase--)...{
        cin>>expr;
        while(operStack.size())operStack.pop();
        operStack.push('#');
        while(dataStack.size())dataStack.pop();
        generateTree(tree,1);
        postOrderTraverse(tree);
        cout<<endl;
        freeTree(tree);
    }
}
 
// 输入格式 #表达式#