A – Pairs Forming LCM

Find the result of the following code:
long long pairsFormLCM( int n ) {
long long res = 0;
for( int i = 1; i <= n; i++ ) for( int j = i; j <= n; j++ ) if( lcm(i, j) == n ) res++; // lcm means least common multiple return res; } A straight forward implementation of the code may time out. If you analyze the code, you will find that the code actually counts the number of pairs (i, j) for which lcm(i, j) = n and (i ≤ j). Input Input sta

A – Pairs Forming LCM最先出现在Python成神之路。