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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 idx = 0;
  8. char input[100];
  9.  
  10. void push(const char *s) {
  11.     strcpy(stack[++top], s);
  12. }
  13.  
  14. void pop() {
  15.     top--;
  16. }
  17.  
  18. void printStack() {
  19.     for (int i = 0; i <= top; i++) printf("%s", stack[i]);
  20.     printf("\n");
  21. }
  22.  
  23. int reduce() {
  24.     if (top >= 2 &&
  25.         strcmp(stack[top-2], "E") == 0 &&
  26.         strcmp(stack[top-1], "+") == 0 &&
  27.         strcmp(stack[top], "E") == 0) {
  28.         pop(); pop(); pop();
  29.         push("E");
  30.         return 1;
  31.     }
  32.  
  33.     if (top!=-1 && stack[top][0]>='a'&&stack[top][0]<='z')
  34.     {
  35.         pop();
  36.         push("E");
  37.         return 1;
  38.     }
  39.  
  40.     if (top >= 2 &&
  41.         strcmp(stack[top-2], "E") == 0 &&
  42.         strcmp(stack[top-1], "*") == 0 &&
  43.         strcmp(stack[top], "E") == 0) {
  44.         pop(); pop(); pop();
  45.         push("E");
  46.         return 1;
  47.     }
  48.  
  49.     if (top >= 2 &&
  50.         strcmp(stack[top-2], "(") == 0 &&
  51.         strcmp(stack[top-1], "E") == 0 &&
  52.         strcmp(stack[top], ")") == 0) {
  53.         pop(); pop(); pop();
  54.         push("E");
  55.         return 1;
  56.     }
  57.  
  58.     return 0;
  59. }
  60.  
  61. int main() {
  62.     fgets(input, sizeof(input), stdin);
  63.  
  64.     while (input[idx]) {
  65.         if (isspace(input[idx])) {
  66.             idx++;
  67.             continue;
  68.         }
  69.  
  70.         char temp[2] = {input[idx], '\0'};
  71.         push(temp);
  72.         idx++;
  73.  
  74.         printf("Shift: ");
  75.         printStack();
  76.  
  77.         while (reduce()) {
  78.             printf("Reduce: ");
  79.             printStack();
  80.         }
  81.     }
  82.  
  83.     if (top == 0 && strcmp(stack[0], "E") == 0)
  84.         printf("String Accepted\n");
  85.     else
  86.         printf("String Rejected\n");
  87.  
  88.     return 0;
  89. }
Success #stdin #stdout 0s 5324KB
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/Wtk5jN
language:
C (gcc 8.3)
created:
14 hours ago
visibility:
public

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