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  1.  
  2. #include <stdio.h>
  3. #include <string.h>
  4. #include <ctype.h>
  5.  
  6. char stack[100][10];
  7. int top = -1;
  8. int pos = 0;   
  9. char input[100];
  10.  
  11.  
  12. void push(const char* s)
  13. {
  14.   strcpy(stack[++top], s);
  15. }
  16.  
  17.  
  18. void pop()
  19. {
  20.     top--;
  21. }
  22.  
  23.  
  24. void printStack()
  25. {
  26.     for (int i = 0; i <= top; i++)
  27.         printf("%s", stack[i]);
  28.     printf("\n");
  29. }
  30.  
  31. // Reduce
  32. int reduce()
  33. {
  34.        if (top != -1 && islower(stack[top][0]))
  35.     {
  36.         pop();
  37.         push("E");
  38.         return 1;
  39.     }
  40.  
  41.  
  42.     if (top >= 2 &&
  43.         strcmp(stack[top - 2], "(") == 0 &&
  44.         strcmp(stack[top - 1], "E") == 0 &&
  45.         strcmp(stack[top], ")") == 0)
  46.     {
  47.         pop(); pop(); pop();
  48.         push("E");
  49.         return 1;
  50.     }
  51.  
  52.  
  53.     if (top >= 2 &&
  54.         strcmp(stack[top - 2], "E") == 0 &&
  55.         strcmp(stack[top - 1], "*") == 0 &&
  56.         strcmp(stack[top], "E") == 0)
  57.     {
  58.         pop(); pop(); pop();
  59.         push("E");
  60.         return 1;
  61.     }
  62.  
  63.  
  64.     if (top >= 2 &&
  65.         strcmp(stack[top - 2], "E") == 0 &&
  66.         strcmp(stack[top - 1], "+") == 0 &&
  67.         strcmp(stack[top], "E") == 0)
  68.     {
  69.         pop(); pop(); pop();
  70.         push("E");
  71.         return 1;
  72.     }
  73.  
  74.     return 0;
  75. }
  76.  
  77. int main()
  78. {
  79.  
  80.     fgets(input, sizeof(input), stdin);
  81.  
  82.     while (input[pos])
  83.     {
  84.  
  85.         if (input[pos] == ' ' || input[pos] == '\n')
  86.         {
  87.             pos++;
  88.             continue;
  89.         }
  90.  
  91.         // SHIFT
  92.         char temp[2] = { input[pos], '\0' };
  93.         push(temp);
  94.         pos++;
  95.  
  96.         printf("Shift: ");
  97.         printStack();
  98.  
  99.         // REDUCE
  100.         while (reduce())
  101.         {
  102.             printf("Reduce: ");
  103.             printStack();
  104.         }
  105.     }
  106.  
  107.  
  108.     while (reduce())
  109.     {
  110.         printf("Reduce: ");
  111.         printStack();
  112.     }
  113.  
  114.  
  115.     if (top == 0 && strcmp(stack[0], "E") == 0)
  116.         printf("String Accepted\n");
  117.     else
  118.         printf("String Rejected\n");
  119.  
  120.     return 0;
  121. }
Success #stdin #stdout 0s 5264KB
comments (?)
stdin
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a+s*a
stdout
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Shift: a
Reduce: E
Shift: E+
Shift: E+s
Reduce: E+E
Reduce: E
Shift: E*
Shift: E*a
Reduce: E*E
Reduce: E
String Accepted
https://ideone.com/zwfY4t
language:
C++14 (gcc 8.3)
created:
13 hours ago
visibility:
public

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