poj: 2255

跟LEETCODE的preorder，inorder转postorder题很像

 #include <iostream>
 #include <stdio.h>
 #include <string>
 #include <stack>
 #include <map>
 #include <vector>
 #include <algorithm>
 using namespace std;

 struct node {
     char val;
     node *left, *right;
     node(char v) : val(v), left(NULL), right(NULL) { }
 };

 node* preIn(string preorder, string inorder, int prebeg, int inbeg, int len) {
     if (!len) return NULL;
     node *tmp = new node(preorder[prebeg]);
     int leftlen, rightlen;
     for (int i = inbeg; i < inbeg+len; ++i) {
         if (tmp->val == inorder[i]) {
             leftlen = i - inbeg;
             rightlen = len - leftlen - ;
             break;
         }
     }
     tmp->left = preIn(preorder, inorder, prebeg+, inbeg, leftlen);
     tmp->right = preIn(preorder, inorder, prebeg+leftlen+, inbeg+leftlen+, rightlen);
     return tmp;
 }

 string postString(node *root) {
     if (!root) return "";
     return postString(root->left) + postString(root->right) + root->val;
 }

 int main()
 {
     string preorder, inorder;
     while (cin >> preorder && cin >> inorder) {
         node *root = preIn(preorder, inorder, , , preorder.size());
         string postorder = postString(root);
         cout << postorder << endl;
     }

     ;
 }