1 #include <iostream>
  2 #include <cstdio>
  3 
  4 
  5 using namespace std;
  6 
  7 struct Node
  8 {
  9     bool have_value;
 10     int w;
 11     int d;
 12 
 13     Node *left,*right;
 14 
 15     Node():left(NULL),right(NULL),have_value(false){}
 16 };
 17 
 18 Node* newnode() { return new Node(); }
 19 
 20 void remove_tree(Node* root)
 21 {
 22     if(root==NULL) return;
 23 
 24     remove_tree(root->left);
 25     remove_tree(root->right);
 26 
 27     delete root;
 28 }
 29 
 30 Node* built_tree(Node* root)
 31 {
 32     int wl,wr,dl,dr;
 33     cin>>wl>>dl>>wr>>dr;                    //建树过程中要注意全局变量的使用,如果换成全局变量,wl等不会被push进堆栈段从而导致数据丢失
 34     if(wl==0)
 35     {
 36         Node *rl=newnode();
 37         rl->d=dl;
 38         root->left=built_tree(rl);
 39     }
 40     if(wr==0)
 41     {
 42         Node *rr=newnode();
 43         rr->d=dr;
 44         root->right=built_tree(rr);
 45     }
 46     if(wl!=0 )
 47     {
 48         Node* lu=newnode();
 49 
 50         lu->w=wl;
 51         lu->d=dl;
 52         lu->have_value=http://www.mamicode.com/true;
 53         root->left=lu;
 54     }
 55     if(wr!=0)
 56     {
 57         Node* ru=newnode();
 58 
 59         ru->w=wr;
 60         ru->d=dr;
 61         ru->have_value=http://www.mamicode.com/true;
 62         root->right=ru;
 63     }
 64     return root;
 65 }
 66 
 67 
 68 int postsum(Node* root)
 69 {
 70     
 71 }
 72 
 73 
 74 int main()
 75 {
 76     for(;;)
 77     {
 78         Node *root;
 79         remove_tree(root);
 80         root=newnode();
 81 
 82         built_tree(root);
 83 
 84         Node* rl=root->left;
 85         Node* rr=root->right;
 86 
 87         int pl=0;
 88         postsum(rl);
 89         int pr=0;
 90         postsum(rr);
 91 
 92         //cout<<pl<<" "<<pr<<endl;
 93 
 94         if((rl->d)*pl==(rr->d)*pr)
 95             cout<<"YES"<<endl;
 96         else
 97             cout<<"NO"<<endl;
 98         
 99     }
100 }

#include <iostream>
#include <cstdio>

using namespace std;

bool solve(int& w)
{
    int wl,wr,dl,dr;
    cin>>wl>>dl>>wr>>dr;

    bool b1=true,b2=true;
    if(!wl) b1=solve(wl);
    if(!wr) b2=solve(wr);

    w=wl+wr;

    return b1 && b2 && (wl*dl==wr*dr);
}

int main()
{
    int w;
    bool bvar=solve(w);

    if(bvar)
        printf("%s\n", "YES");
    else
        printf("%s\n", "NO");
}