WPL：所有叶结点带权路径长度之和。

思路：

递归思想，先序遍历框架。

代码：

int WPL=0;
int preOrder(BTNode *root,int level){//先序遍历框架if(root){if(root->left==NULL&&root->right==NULL)//如果是叶结点，累计WPLWPL+=level*root->weight;if(root->left!=NULL)preOrder(root->left,level+1);if(root->right!=NULL)preOrder(root->right,level+1);}return WPL;
}

测试：

#include<stdio.h>
#include <stdlib.h>
#include<math.h>	//数学函数，求平方根、三角函数、对数函数、指数函数...#define MAXSIZE 100//用于使用c++的输出语句
#include<iostream>
using namespace std;typedef struct BTNode    
{int weight;struct BTNode *left;struct BTNode *right;
}BTNode;void createBiTree(BTNode* &T);
int preOrder(BTNode *root,int level);
int WPL=0;
void main(){BTNode *t;createBiTree(t);cout<<endl;cout<<preOrder(t,0)<<endl;
}int preOrder(BTNode *root,int level){//先序遍历框架if(root){if(root->left==NULL&&root->right==NULL)//如果是叶结点，累计WPLWPL+=level*root->weight;if(root->left!=NULL)preOrder(root->left,level+1);if(root->right!=NULL)preOrder(root->right,level+1);}return WPL;
}void createBiTree(BTNode* &T)
{int  num;cin>>num;if(num==-1) T=NULL;else{T=(BTNode *)malloc(sizeof(BTNode));T->weight=num;cout<<"put in \'"<<T->weight<<"\' lchild"<<endl;createBiTree(T->left);cout<<"put in \'"<<T->weight<<"\' rchild"<<endl;createBiTree(T->right);}
}