Educational Codeforces Round 52 (Rated for Div. 2)A,B,CC题：贪心+约束差分模板

Posted 2021-03-16 pengge666

 

 水题。仔细看题

 1 #include<bits/stdc++.h>
 2  
 3 using namespace std;
 4 #define int long long
 5 signed main(){
 6     int _;
 7     cin>>_;
 8     while(_--){
 9         int s,a,b,c;
10         cin>>s>>a>>b>>c;
11         int ans=0;
12         ans=(s/(a*c))*a+(s/(a*c))*b+(s%(a*c))/c;
13         cout<<ans<<‘
‘;
14     }
15     
16     return 0;
17 } 

 

 

 思路：找规律

 1 #include<bits/stdc++.h>
 2  
 3 using namespace std;
 4 #define int long long
 5 signed main(){
 6     
 7     int n,m;
 8     cin>>n>>m;
 9     
10     int ans1=n-min(m*2,n);
11     int ans2=0;
12     for(int i=0;;i++){
13         int cnt=(i-1)*(i)/2;
14         if(cnt>=m){
15             ans2=i;break;
16         }
17     }
18     cout<<ans1<<" "<<n-ans2;
19     return 0;
20 }

 

 

 

 思路：约束差分进行O（n）的处理。然后贪心。

 1 #include<bits/stdc++.h>
 2 
 3 using namespace std;
 4 #define int long long
 5 #define N 666666
 6 int H[N];int vis[N];//vis数组的定义：高度为I的有VIS[I]个
 7 signed main(){
 8     int n,k;
 9     cin>>n>>k;
10     int maxn=0;
11     for(int i=1;i<=n;i++){
12         scanf("%lld",&H[i]);
13         maxn=max(maxn,H[i]);
14         vis[0]++;
15         vis[H[i]+1]--;
16     }
17     for(int i=1;i<=N;i++){
18         vis[i]+=vis[i-1];
19     }
20     int ans=0;int sum=0;
21 /*    for(int i=1;i<=maxn;i++){//
22         cout<<vis[i]<<" ";
23     }
24     cout<<‘
‘;
25     */
26     for(int i=maxn;i>=1;i--){
27         if(vis[i]>=n){
28             if(sum) 
29                 ans++;
30             break;
31         }
32         if(sum+vis[i]<=k){
33             sum+=vis[i];
34         }else{
35             ans++;
36             sum=vis[i];
37         }
38     }
39     cout<<ans;
40     return 0;
41 }