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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <ctype.h>
  4.  
  5. char stack[100][10];
  6. int top = -1;
  7. int index = 0;
  8. char input[100];
  9.  
  10. void removeSpaces(char *str)
  11. {
  12.     int i = 0, j = 0;
  13.  
  14.     while (str[i] != '\0')
  15.     {
  16.         if (!isspace(str[i]))
  17.         {
  18.             str[j] = str[i];
  19.             j++;
  20.         }
  21.         i++;
  22.     }
  23.     str[j] = '\0';
  24. }
  25.  
  26. void push(const char *s)
  27. {
  28.     strcpy(stack[++top], s);
  29. }
  30.  
  31. void pop()
  32. {
  33.     top--;
  34. }
  35.  
  36. void printStack()
  37. {
  38.     for (int i = 0; i <= top; i++)
  39.         printf("%s", stack[i]);
  40.     printf("\n");
  41. }
  42.  
  43. int reduce()
  44. {
  45.     if (top >= 2 &&
  46.         strcmp(stack[top - 2], "E") == 0 &&
  47.         strcmp(stack[top - 1], "+") == 0 &&
  48.         strcmp(stack[top], "E") == 0)
  49.     {
  50.         pop();
  51.         pop();
  52.         pop();
  53.         push("E");
  54.         return 1;
  55.     }
  56.  
  57.     if (top >= 2 &&
  58.         strcmp(stack[top - 2], "E") == 0 &&
  59.         strcmp(stack[top - 1], "*") == 0 &&
  60.         strcmp(stack[top], "E") == 0)
  61.     {
  62.         pop();
  63.         pop();
  64.         pop();
  65.         push("E");
  66.         return 1;
  67.     }
  68.  
  69.     if (top >= 2 &&
  70.         strcmp(stack[top - 2], "(") == 0 &&
  71.         strcmp(stack[top - 1], "E") == 0 &&
  72.         strcmp(stack[top], ")") == 0)
  73.     {
  74.         pop();
  75.         pop();
  76.         pop();
  77.         push("E");
  78.         return 1;
  79.     }
  80.  
  81.     if (top != -1 && stack[top][0] >= 'a' && stack[top][0] <= 'z')
  82.     {
  83.         pop();
  84.         push("E");
  85.         return 1;
  86.     }
  87.  
  88.     return 0;
  89. }
  90.  
  91. int main()
  92. {
  93.     fgets(input, sizeof(input), stdin);
  94.     input[strcspn(input, "\n")] = '\0';
  95.     removeSpaces(input);
  96.  
  97.     while (input[index])
  98.     {
  99.         char temp[2] = {input[index], '\0'};
  100.         push(temp);
  101.         index++;
  102.  
  103.         printf("Shift: ");
  104.         printStack();
  105.  
  106.         while (reduce())
  107.         {
  108.             printf("Reduce: ");
  109.             printStack();
  110.         }
  111.     }
  112.  
  113.     if (top == 0 && strcmp(stack[0], "E") == 0)
  114.         printf("String Accepted\n");
  115.     else
  116.         printf("String Rejected\n");
  117.  
  118.     return 0;
  119. }
Success #stdin #stdout 0s 5316KB
comments (?)
stdin
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(a + (b*a))
stdout
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Shift: (
Shift: (a
Reduce: (E
Shift: (E+
Shift: (E+(
Shift: (E+(b
Reduce: (E+(E
Shift: (E+(E*
Shift: (E+(E*a
Reduce: (E+(E*E
Reduce: (E+(E
Shift: (E+(E)
Reduce: (E+E
Reduce: (E
Shift: (E)
Reduce: E
String Accepted
https://ideone.com/ey6OOX
language:
C (gcc 8.3)
created:
8 hours ago
visibility:
public

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