acdream LCM Challenge (最小公倍数)

 1 /*
 2 * this code is made by xcw0754
 3 * Problem: 1077
 4 * Verdict: Accepted
 5 * Submission Date: 2015-07-16 10:24:02
 6 * Time: 0MS
 7 * Memory: 1672KB
 8 */
 9 #include <bits/stdc++.h>
10 #define LL long long
11 #define pii pair<int,int>
12 #define INF 0x7f7f7f7f
13 using namespace std;
14 const int N=200000+50;
15  
16 LL cal(LL n)    //偶数
17 {
18     LL ans=0;
19     //n n-1 n-3
20     if(__gcd(n,n-3)==1) ans=max(ans, n*(n-1)*(n-3));
21  
22     //n-1 n-2 n-3
23     ans=max(ans, (n-1)*(n-2)*(n-3));
24  
25     return ans;
26 }
27  
28  
29 int main()
30 {
31     //freopen("input.txt", "r", stdin);
32     LL n;
33     scanf("%lld",&n);
34     if(n==1)    printf("1\n");
35     else if(n==2)    printf("2\n");
36     else if(n==3)    printf("6\n");
37     else if(n==4)    printf("12\n");
38     else if(n==5)    printf("60\n");
39     else
40     {
41         if((n&1)==0)    cout<<cal(n)<<endl;
42         else    cout<<n*(n-1)*(n-2)<<endl;
43     }
44     return 0;
45 }