Happy Number
1 #include <stdio.h> 2 #include <string.h> 3 4 int main() 5 { 6 long long n, x, sum; 7 scanf("%lld", &n); 8 x = n; 9 10 sum = 0; 11 while(x>0) 12 { 13 sum = sum + (x%10) * (x%10); 14 x /= 10; 15 } 16 x = sum; 17 18 while(x!=n&&x!=4&&x!=1) 19 { 20 sum = 0; 21 while(x>0) 22 { 23 sum = sum + (x%10) * (x%10); 24 x /= 10; 25 } 26 x = sum; 27 } 28 if(x==1) printf("HAPPY\n"); 29 else printf("UNHAPPY\n"); 30 return 0; 31 }