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  1. #include <stdio.h>
  2. #define SIZE 100
  3.  
  4. int stack[SIZE],
  5.     level,
  6.     n,
  7.     k;
  8.  
  9. void init(){
  10.  
  11.      stack[level] = 0;
  12. };
  13.  
  14. int valid() {
  15.  
  16.     int i;
  17.  
  18.     for(i = 1; i < level; i++) 
  19.  
  20.         if(stack[i] == stack[level]) return 0;
  21.  
  22.     return 1;
  23. };
  24.  
  25. int succ() {
  26.  
  27.     if(stack[level]<n){
  28.  
  29.        stack[level]++;
  30.  
  31.        return 1;  
  32.     }
  33.     return 0;
  34. };
  35.  
  36. int sol() {
  37.  
  38.     return level == k; 
  39. };
  40.  
  41. void print() {
  42.  
  43.     int i;
  44.  
  45.     printf("x    | ");
  46.     for(i = 1; i <= k; i++) printf("%d ", i);
  47.     printf("\n----------------\n");
  48.     printf("f(x) | ");
  49.     for(i = 1; i <= k; i++) printf("%d ", stack[i]);
  50.     printf("\n\n");           
  51. };
  52.  
  53. void bt() {
  54.  
  55.     int hs,is;
  56.  
  57.     level = 1;
  58.  
  59.     while(level > 0) {
  60.  
  61.           hs = 1; is = 0;
  62.  
  63.           while(hs && !is) {
  64.  
  65.                 hs = succ();
  66.  
  67.                 if(hs) is = valid();                   
  68.           } 
  69.  
  70.           if(hs) {
  71.  
  72.             if(sol()) print();
  73.  
  74.                 else {level++;init();}                
  75.  
  76.           } else level--;  
  77.     }
  78.  
  79. };
  80.  
  81. void printSet(char set, int n, int flag) {
  82.  
  83.      int i;
  84.  
  85.      if( flag ) printf("f : A -> B\n\n");
  86.  
  87.      printf("%c = {",set);
  88.  
  89.      for(i = 1; i <= n; i++) {
  90.  
  91.          printf("%d ",i);         
  92.      }
  93.  
  94.      printf("}\n\n");
  95. };
  96.  
  97. int main() {
  98.  
  99.     //freopen("genAllInjective.out","w",stdout);
  100.  
  101.     printf("%s\n\n","Generating All The Injective Functions");
  102.     //f : A -> B
  103.     //A = {1,2}, B = {1,2,3}
  104.     scanf("%d",&n);
  105.     scanf("%d",&k);
  106.  
  107.     printSet('A',k, 1);
  108.     printSet('B',n, 0);
  109.  
  110.     bt();    
  111.  
  112. return(0);
  113. };
Success #stdin #stdout 0s 5304KB
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stdout
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Generating All The Injective Functions

f : A -> B

A = {1 2 3 }

B = {1 2 3 4 }

x    | 1 2 3 
----------------
f(x) | 1 2 3 

x    | 1 2 3 
----------------
f(x) | 1 2 4 

x    | 1 2 3 
----------------
f(x) | 1 3 2 

x    | 1 2 3 
----------------
f(x) | 1 3 4 

x    | 1 2 3 
----------------
f(x) | 1 4 2 

x    | 1 2 3 
----------------
f(x) | 1 4 3 

x    | 1 2 3 
----------------
f(x) | 2 1 3 

x    | 1 2 3 
----------------
f(x) | 2 1 4 

x    | 1 2 3 
----------------
f(x) | 2 3 1 

x    | 1 2 3 
----------------
f(x) | 2 3 4 

x    | 1 2 3 
----------------
f(x) | 2 4 1 

x    | 1 2 3 
----------------
f(x) | 2 4 3 

x    | 1 2 3 
----------------
f(x) | 3 1 2 

x    | 1 2 3 
----------------
f(x) | 3 1 4 

x    | 1 2 3 
----------------
f(x) | 3 2 1 

x    | 1 2 3 
----------------
f(x) | 3 2 4 

x    | 1 2 3 
----------------
f(x) | 3 4 1 

x    | 1 2 3 
----------------
f(x) | 3 4 2 

x    | 1 2 3 
----------------
f(x) | 4 1 2 

x    | 1 2 3 
----------------
f(x) | 4 1 3 

x    | 1 2 3 
----------------
f(x) | 4 2 1 

x    | 1 2 3 
----------------
f(x) | 4 2 3 

x    | 1 2 3 
----------------
f(x) | 4 3 1 

x    | 1 2 3 
----------------
f(x) | 4 3 2
https://ideone.com/gWGseA
Generating Injective Functions.
language:
C++ (gcc 8.3)
created:
274 days ago
visibility:
secret

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