problem:
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
Find the largest palindrome made from the product of two 3-digit numbers.
বাংলা প্রবলেম, তবে একটা সমস্যা execution time অনেক বেড়ে যাবে যদি লুপ দিয়ে করেন। যাই হোক নিচের কোডটি যথেষ্ট efficient।
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| #include<stdio.h> | |
| int reverse(int n){ | |
| int reversed=0; | |
| while(n>0){ | |
| reversed=10*reversed+(n%10); | |
| n=n/10; | |
| } | |
| return reversed; | |
| } | |
| int is_pal(int n){ | |
| if(n==reverse(n)) | |
| return n; | |
| else | |
| return 0; | |
| } | |
| int main() | |
| { | |
| int lar_pal=0; | |
| int a=999;int b; | |
| while(a>100){ | |
| b=999; | |
| while(b>=a){ | |
| if(a*b<=lar_pal) | |
| break; | |
| if(is_pal(a*b)) | |
| lar_pal=a*b; | |
| b--; | |
| } | |
| a--; | |
| } | |
| printf("%d\n",lar_pal); | |
| } |
