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Sellak_Project 2.c

@@ -0,0 +1,189 @@
+//Sofya_Sellak
+#include <stdio.h>
+#include <string.h>
+#define MAX 100
+
+typedef struct _node{
+    char key;
+    struct _node* left;
+    struct _node* right;
+}node;
+
+node* atree(char* postfix);
+void transfer(char* infix, char* postfix);
+void inorder(node* root);
+void preorder(node* root);
+void postorder(node* root);
+int priority(char top, char c);
+void menu(void);
+
+
+int main(){
+node*root;
+char input[MAX];
+char infix[MAX];
+char postfix[MAX];
+int i,j,el;
+
+menu();
+scanf("%d",&el);
+
+ do
+  {
+
+  switch(el){
+  case 1:
+    printf("enter inorder expression\n");
+    gets(input);
+    j = 0;
+    for(i = 0;i< strlen(input);i++)
+     {
+        if(input[i] != ' ')
+          {
+            infix[j] = input[i];
+            j++;
+           }
+        infix[j]= '\0';
+     }
+    transfer(infix, postfix);
+    root= atree(postfix);
+
+      break;
+  case 2:
+      inorder(root);
+      printf("\n");
+
+      break;
+  case 3:
+      preorder(root);
+      printf("\n");
+
+      break;
+  case 4:
+      postorder(root);
+      printf("\n");
+
+      break;
+    default :
+    printf("Error\n");
+  }
+  menu();
+  scanf("%d",&el);
+  } while(el!= 5);
+       printf("End\n");
+}
+
+void transfer (char* infix, char* postfix){
+    char operators[MAX];
+    int top = -1;
+    int i, j = 0;
+
+    for(i = 0;i< strlen(infix);i++){
+        if( isalpha (infix[i]) != 0){
+            postfix[j++] = infix[i];
+        }
+        else{
+            if(top == -1 || priority(operators[top],infix[i]) == 1){
+                operators[++top] = infix[i];
+            }
+            else if(priority(operators[top],infix[i]) == 2 || priority(operators[top],infix[i]) ==  0){
+                while(priority(operators[top],infix[i]) != 1){
+                    postfix[j++] = operators[top--];
+                    if(top == -1)
+                        break;
+                }
+                operators[++top] = infix[i];
+            }
+        }
+    }
+    while(top != -1){
+        postfix[j++] = operators[top--];
+    }
+    postfix[j] = '\0';
+}
+
+int priority(char top, char c){
+    if(top == '-' || top == '+'){
+       if(c == '*' || c == '/'){
+        return 1;
+       }
+    }
+    if(top == '*' || top == '/'){
+       if (c == '+' || c == '-'){
+         return 2;
+       }
+    }
+    else{
+         return 0;
+        }
+ }
+
+node* atree(char* postfix){
+    node* operators[MAX];
+    node *new1,*ptr1, *ptr2;
+    int top = -1, i;
+
+    for(i = 0;i< strlen(postfix);i++){
+        if(isalpha (postfix[i]) != 0){
+            new1 = (node*)malloc(sizeof(node));
+            new1->key = postfix[i];
+            new1->left = NULL;
+            new1->right = NULL;
+            operators[++top] = new1;
+        }
+        else{
+            new1 = (node*)malloc(sizeof(node));
+            ptr1 = (node*)malloc(sizeof(node));
+            ptr2 = (node*)malloc(sizeof(node));
+            ptr1 = operators[top--];
+            ptr2 = operators[top--];
+            new1->key = postfix[i];
+            new1->left = ptr2;
+            new1->right = ptr1;
+            operators[++top] = new1;
+        }
+    }
+    return(new1);
+}
+
+
+void inorder(node* root){
+    if(root == NULL)
+        return;
+    else{
+        inorder(root->left);
+        printf("%c", root->key);
+        inorder(root->right);
+    }
+}
+
+
+void preorder(node* root){
+    if(root == NULL)
+        return;
+    else{
+        printf("%c", root->key);
+        preorder(root->left);
+        preorder(root->right);
+    }
+}
+
+
+void postorder(node* root){
+    if(root == NULL)
+        return;
+    else{
+        postorder(root->left);
+        postorder(root->right);
+        printf("%c", root->key);
+    }
+}
+
+void menu(void){
+printf("***************Menu*************\n");
+printf("1- Enter Inorder Expression\n");
+printf("2- 'Inorder' traversal\n");
+printf("3- 'Preorder' traversal\n");
+printf("4- 'Postorder' traversal\n");
+printf("5- Quit\n");
+}