pat04-Tree 7. Search in a Binary search Tree (25)

04-Tree 7. Search in a Binary search Tree (25) time limit MS Memory limit 65536 KB code length limit 8000 B procedure StandardAuthor Chen, Yue

To search a key in a binary search tree, we start from the root and move all the choosing branches according to The comparison results of the keys. The searching path corresponds to a sequence of keys. For example, following {1, 4, 2, 3} We can find 3 from a binary search tree with 1 as its root. But {2, 4, 1, 3} are not such a path since 1 are in the right subtree of the root 2, which breaks the rule for a binary sear Ch Tree. Now given a sequence of keys, you is supposed to tell whether or not it indeed correspnds to a searching path in a binary Search tree.

Input Specification:

Each input file contains the one test case. The first line gives positive integers N and M (<=100) which is the total number of sequences, and The size of each sequence, respectively. Then N lines follow, each gives a sequence of keys. It is assumed, the keys numbered from 1 to M.

Output Specification:

For each sequence, print with a line "YES" if the sequence does correspnd to a searching path in a binary search tree, or "N O "if not.

Sample Input:

3 41 4 2 32 4 1 33 2 4 1

Sample Output:

Yesnono

Submit Code

Law One:

If it is a two-fork search tree, in addition to the leaf nodes in the tree, each node of the left and right sub-tree must have one empty, the other tree is not empty.

1#include <cstdio>2#include <algorithm>3#include <iostream>4#include <cstring>5#include <queue>6#include <vector>7 using namespacestd;8 structnode{9     intv;TenNode *l,*R; One node () { AL=r=NULL; -     } - }; the intMain () { -     //freopen ("D:\\input.txt", "R", stdin); -     intn,m; -scanf"%d%d",&n,&m); +      while(n--){ -queue<int>Q; +         intI,num; ANode *p,*pp,*h=NULL; at          for(i=0; i<m;i++){ -scanf"%d",&num); - Q.push (num); -         } -H=Newnode (); -h->v=Q.front (); in Q.pop (); -          for(i=1; i<m;i++){ tonum=Q.front (); + Q.pop (); -p=h; the              while(p) { *Pp=p;//pp point to the father of P $                 if(num>p->v&&p->l==NULL) {Panax NotoginsengP=p->R; -                 } the                 Else{ +                     if(num<p->v&&p->r==NULL) { AP=p->l; the                     } +                     Else -                          Break;//prevent elements from being equal $                 } $             } -             if(p==NULL) { -p=Newnode (); thep->v=num; -                 if(num>pp->v) {WuyiPp->r=p; the                 } -                 Else{ WuPp->l=p; -                 } About             } $             Else{ -                  Break; -             } -         } A         if(i==m) { +printf"yes\n"); the         } -         Else{ $printf"no\n"); the         } the     } the     return 0; the}

Law II:

First, according to test instructions achievements, get the tree, with the last number of input to the tree traversal, if the last m times to find a matching leaf node, the sequence is correct; otherwise, the sequence is wrong.

1#include <cstdio>2#include <algorithm>3#include <iostream>4#include <cstring>5#include <queue>6#include <vector>7 using namespacestd;8 structnode{9     intv;TenNode *l,*R; One node () { AL=r=NULL; -     } - }; the intMain () { -     //freopen ("D:\\input.txt", "R", stdin); -     intn,m; -scanf"%d%d",&n,&m); +      while(n--){ -queue<int>Q; +         intI,num,wantfind; ANode *p,*pp,*h; at          for(i=0; i<m;i++){ -scanf"%d",&num); - Q.push (num); -         } -Wantfind=num;//last one -H=Newnode (); inh->v=Q.front (); - Q.pop (); to          for(i=1; i<m;i++) {//Achievements +num=Q.front (); - Q.pop (); thep=h; *              while(p) { $Pp=p;//pp point to the father of PPanax Notoginseng                 if(num>p->v) { -P=p->R; the                 } +                 Else{ AP=p->l; the                 } +             } -p=Newnode (); $p->v=num; $             if(num>pp->v) { -Pp->r=p; -             } the             Else{ -Pp->l=p;Wuyi             } the         } -         intCount=0; Wup=h; -          while(p) { About             if(wantfind>p->v) { $P=p->R; -             } -             Else{ -P=p->l; A             } +count++; the         } -         if(count==L) { $printf"yes\n"); the         } the         Else{ theprintf"no\n"); the         } -     } in     return 0; the}

pat04-Tree 7. Search in a Binary search Tree (25)