Codeforces Round #511 (Div. 2) C. Enlarge GCD
链接:https://codeforces.com/contest/1047/problem/C
题意:给你n个数,删掉尽可能少的数,使公共gcd更大
题解:思想还是采用暴力枚举的思想,因为要使gcd更大,从gcd+1开始枚举,找出原序列中所有当前是gcd的倍数的数,最后n减去就是答案
代码:
1 //#include<bits/stdc++.h> 2 #include<iostream> 3 #include<vector> 4 #include<stack> 5 #include<string> 6 #include<cstdio> 7 #include<algorithm> 8 #include<queue> 9 #include<map> 10 #include<set> 11 #include<cmath> 12 #include<iomanip> 13 #define inf 0x3f3f3f3f 14 using namespace std; 15 typedef long long ll; 16 const int M = int(1e7)*2 + 5; 17 int a[M],b[M]; 18 int gcd(int a, int b) 19 { 20 return b ? gcd(b, a % b) : a; 21 } 22 signed main() 23 { 24 int n; cin >> n; 25 int g; 26 int maxn = -1; 27 for (int i = 0; i < n; i++){ 28 int x; cin >> x; 29 a[x]++; 30 if (i == 0) 31 g = x; 32 else 33 g = gcd(g, x); 34 maxn = max(maxn, x); 35 } 36 int ans = 0; 37 for (int i = g + 1; i <= maxn; i++){ 38 if (!b[i]){ 39 int cnt = 0; 40 for (int j = i; j <= maxn; j += i) { 41 b[j] = 1; 42 cnt += a[j]; 43 } 44 ans = max(ans, cnt); 45 } 46 } 47 if (ans == 0) cout << -1 << endl; 48 else cout << n - ans << endl; 49 return 0; 50 }
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心里有光,哪儿都美
心里有光,哪儿都美