"Data structure and algorithm analysis--c language description" after reading note 8

Two-fork Tree

The leaf of the expression tree is the operand (operand), such as a constant or variable, while the other node is the operator (operator). Here the qualified operator can only be +,-,*,/four operators.

To transform a suffix expression into an expression tree:

Program:

Expression_tree.h

struct treenode;typedef struct TreeNode *ptrtonode;typedef ptrtonode tree;typedef char Type;    Ptrtonode createnode (char ch); struct treenode{Type Element;    Tree left; Tree right;};

Expression_tree.c

#include "expression_tree.h" #include <stdlib.h> #include <stdio.h>ptrtonode createnode (char ch) {    Ptrtonode p=malloc (sizeof (struct TreeNode));    if (p==null) {printf ("The node is NULL!\n"); return p;    } p->element=ch; return p; }

Stack.h

#include "expression_tree.h" typedef tree ElementType; #ifndef _stack_hstruct node;typedef struct Node *stack;int IsEmpty (stack s); int isfull (stack s); Stack createstack (int maxelements); void Disposestack (stack s); void Makeempty (stack s); void Push (ElementType X, Stack s) ; ElementType Top (stack s); void Pop (stack s);    ElementType Topandpop (Stack S), #define EMPTYTOS ( -1) #define MINSTACKSIZE (5) struct node{int capacity;    int topofstack; ElementType *array;}; #endif

Stack.c

#include   "stack.h" #include <stdio.h> #include <error.h> #include <stdlib.h>int isempty ( Stack s) {    return s->topofstack==emptytos;} Int isfull (stack s) {    return s->topofstack== (S->Capacity-1);} Stack createstack ( int MaxElements ) {    stack s;     if (maxelements<minstacksize) error ("Stack size is too small");     s=malloc (sizeof (Struct node)),     if (s==null) error ("Out of  space!!! ");     s->array=malloc (sizeof (ElementType) *maxelements);     if (S-> Array==null) error ("Out of space!!!");     s->capacity=maxelements;    makeempty (S);     return s;} Void disposestack (stack s) {    if (s!=null)  &nbsP;  { free (S->array); free (S);     }}void makeempty (Stack S) {     s->topofstack=emptytos;} Void push (elementtype x,stack s) {    if (Isfull (S)) error ("Full  Stack ");    else    {         s->topofstack++;        s->array[s->topofstack]=x;     }}elementtype top ( stack s) {    if (! IsEmpty (S)) Return s->array[s->topofstack];    error ("empty stack  3 ");     return 0;} Void pop ( stack s) {    if (IsEmpty (S)) error ("Empty stack 2");     else        s->topofstack--;} Elementtype topandpop ( stack s) {    if (!IsEmpty (S))     {return S->Array[ S->TopOfStack--];     }    error ("empty stack 1");     return 0;}

Mainprogram.c

#include <stdio.h> #include <stdlib.h> #include <string.h> #include "stack.h" Tree createtree ( CHAR*&NBSP;STR) {    tree t,p,q;    int len=strlen (str);     stack s=createstack (len);    int i;     for (i=0;i<len;++i)     {switch (str[i])  {    case  ' + ' :    case  '-':    case  ' * ':     case   '/':     {t=createnode (Str[i]);  p=topandpop (s); Q=topandpop (s); t->left=q; t->right=p; Push (t,s); Break;    }    default:    {t=createnode (Str[i]); Push (t,s); Break;    }}    }    return top (S);} Void outtree (tree t) {    if (t!=null)     {         outtree (T->left);         outtree (t-> right);         printf ("%c", t->element);     }} Int main () {    char* ss= "ab+cde+**";     tree tt= Createtree (ss);     outtree (TT);     printf ("\ n");     return 0;}

Use a suffix expression to construct an expression tree, and then output the tree with a post-order traversal policy:

650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M00/71/7D/wKioL1XSk6qghS84AAC9ZiA5MoE590.jpg "title=" capture. JPG "alt=" Wkiol1xsk6qghs84aac9zia5moe590.jpg "/>

"Data structure and algorithm analysis--c language description" after reading note 8