Codeforces Round #539 (Div. 2)

Codeforces Round #539 (Div. 2)

A - Sasha and His Trip

 1 #include<bits/stdc++.h>
 2 #include<iostream>
 3 #include<cstdio>
 4 #include<cstdlib>
 5 #include<cstring>
 6 #include<cmath>
 7 #include<algorithm>
 8 #include<queue>
 9 #include<vector>
10 #include<map>
11 #define lson i<<1
12 #define rson i<<1|1
13 #define LS l,mid,lson
14 #define RS mid+1,r,rson
15 #define mem(a,x) memset(a,x,sizeof(a))
16 #define gcd(a,b) __gcd(a,b)
17 #define ll long long
18 #define ull unsigned long long
19 #define lowbit(x) (x&-x)
20 #define pb(x) push_back(x)
21 #define enld endl
22 #define mian main
23 #define itn int
24 #define prinft printf
25 #pragma GCC optimize(2)
26 //#pragma comment(linker, "/STACK:102400000,102400000")
27 
28 const double PI = acos (-1.0);
29 const int INF = 0x3f3f3f3f;
30 const int EXP = 1e-8;
31 const int N = 1e5 + 5;
32 const int MOD = 1e9 + 7;
33 const int MAXN = 1e5 + 5;
34 
35 using namespace std;
36 
37 int n,v;
38 int main() {
39     cin>>n>>v;
40     if(n-1<=v) {
41         cout<<n-1<<endl;
42         return 0;
43     }
44     int ans=v;
45     for(int i=2;i<=n-1-v+1;++i) ans+=i;
46     cout<<ans<<endl;
47 }

A - Sasha and His Trip

B - Sasha and Magnetic Machines

 1 #include<bits/stdc++.h>
 2 #include<iostream>
 3 #include<cstdio>
 4 #include<cstdlib>
 5 #include<cstring>
 6 #include<cmath>
 7 #include<algorithm>
 8 #include<queue>
 9 #include<vector>
10 #include<map>
11 #define lson i<<1
12 #define rson i<<1|1
13 #define LS l,mid,lson
14 #define RS mid+1,r,rson
15 #define mem(a,x) memset(a,x,sizeof(a))
16 #define gcd(a,b) __gcd(a,b)
17 #define ll long long
18 #define ull unsigned long long
19 #define lowbit(x) (x&-x)
20 #define pb(x) push_back(x)
21 #define enld endl
22 #define mian main
23 #define itn int
24 #define prinft printf
25 #pragma GCC optimize(2)
26 //#pragma comment(linker, "/STACK:102400000,102400000")
27 
28 const double PI = acos (-1.0);
29 const int INF = 0x3f3f3f3f;
30 const int EXP = 1e-8;
31 const int N = 1e5 + 5;
32 const int MOD = 1e9 + 7;
33 const int MAXN = 1e5 + 5;
34 
35 using namespace std;
36 
37 int vis[105],n,sum,tmp,Min;
38 vector<int> p;
39 
40 void init() {
41     mem(vis,0),sum=0,Min=INF;
42 }
43 
44 void Solve(int n) {
45     p.clear();
46     for(int i=2; i<=n; i++) {
47         if(n%i==0) {
48             p.push_back(i);
49         }
50     }
51 }
52 
53 int main() {
54     init();
55     scanf("%d",&n);
56     for(int i=1; i<=n; ++i) {
57         scanf("%d",&tmp);
58         sum+=tmp;
59         vis[tmp]=1;
60         Min=min(Min,tmp);
61     }
62     int ans=sum;
63     for(int i=Min+1; i<=100; ++i)
64         if(vis[i]) {
65             Solve(i);
66             if(p.size()==1) continue;
67             for(int j=0; j<p.size(); ++j) {
68                 ans=min(ans,sum-(i-i/p[j])+Min*p[j]-Min);
69 //                cout<<j<<' '<<p[j]<<endl;
70             }
71         }
72     cout<<ans<<endl;
73 }

B - Sasha and Magnetic Machines

C Sasha and a Bit of Relax

1、交换律

2、结合律（即(a^b)^c == a^(b^c)）

3、对于任何数x，都有x^x=0，x^0=x

4、自反性 A XOR B XOR B = A xor  0 = A

前缀异或

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来源： https://www.cnblogs.com/chunibyo/p/10398059.html