CF1183 F
I'm going to give you n numbers. I'm going to ask you to select at most 3 numbers. The numbers that don't divide each other make the sum the maximum.
The method is to enumerate a selected number x from large to small
And then he never divides all his numbers by the largest y
And then never divide the two numbers x and y by the largest number z.
Why do you have to choose the biggest one?
From this point of view
If the maximum number m is not a multiple of the next largest number m, then you can take the maximum and the second largest directly.
If the largest number m is a multiple of the next largest number m, then the smallest multiple 2
Secondary large + secondary large < secondary large + secondary large < = maximum
So choose the biggest
And then discretize the same thing, because the same things are bound to divide each other.
/* if you can't see the repay Why not just work step by step rubbish is relaxed to ljq */ #include <cstdio> #include <cstring> #include <iostream> #include <queue> #include <cmath> #include <map> #include <stack> #include <set> #include <sstream> #include <vector> #include <stdlib.h> #include <algorithm> using namespace std; #define dbg(x) cout<<#x<<" = "<< (x)<< endl #define dbg2(x1,x2) cout<<#x1<<" = "<<x1<<" "<<#x2<<" = "<<x2<<endl #define dbg3(x1,x2,x3) cout<<#x1<<" = "<<x1<<" "<<#x2<<" = "<<x2<<" "<<#x3<<" = "<<x3<<endl #define max3(a,b,c) max(a,max(b,c)) #define min3(a,b,c) min(a,min(b,c)) typedef pair<int,int> pll; typedef long long ll; const int inf = 0x3f3f3f3f; const int _inf = 0xc0c0c0c0; const ll INF = 0x3f3f3f3f3f3f3f3f; const ll _INF = 0xc0c0c0c0c0c0c0c0; const ll mod = (int)1e9+7; ll gcd(ll a,ll b){return b?gcd(b,a%b):a;} ll ksm(ll a,ll b,ll mod){int ans=1;while(b){if(b&1) ans=(ans*a)%mod;a=(a*a)%mod;b>>=1;}return ans;} ll inv2(ll a,ll mod){return ksm(a,mod-2,mod);} void exgcd(ll a,ll b,ll &x,ll &y,ll &d){if(!b) {d = a;x = 1;y=0;}else{exgcd(b,a%b,y,x,d);y-=x*(a/b);}}//printf("%lld*a + %lld*b = %lld\n", x, y, d); /*namespace sgt { #define mid ((l+r)>>1) #undef mid }*/ const int MAX_N = 200025; int arr[MAX_N]; int main() { //ios::sync_with_stdio(false); //freopen("a.txt","r",stdin); //freopen("b.txt","w",stdout); int t; scanf("%d",&t); while(t--) { int n,ans = 0; scanf("%d",&n); for(int i = 1;i<=n;++i) scanf("%d",&arr[i]); sort(arr+1,arr+1+n); int sz = unique(arr+1,arr+1+n)-arr-1; for(int i = sz;i>=1;--i) { ans = max(ans,arr[i]); for(int j = i-1;j>=1;--j) { if(arr[i]%arr[j]!=0) { ans = max(ans,arr[i]+arr[j]); for(int k = j-1;k>=1;--k) { if(arr[i]%arr[k]!=0&&arr[j]%arr[k]!=0) { ans = max(ans,arr[i]+arr[j]+arr[k]); break; } } break; } } } printf("%d\n",ans); } //fclose(stdin); //fclose(stdout); //cout << "time: " << (long long)clock() * 1000 / CLOCKS_PER_SEC << " ms" << endl; return 0; }