Educational Codeforces Round 158 (Rated for Div. 2)

A

EDU的题总是感觉写起来怪怪的

#include <bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;

int a[101];

void solve(){
    int n,x;
    cin>>n>>x;
    int ans=0;
    for(int i=1;i<=n;i++) cin>>a[i];
    a[++n]=x;
    ans=2*(x-a[n-1]);
    for(int i=1;i<=n;i++){
        int cnt=a[i]-a[i-1];
        ans=max(ans,cnt);
    }
    cout<<ans<<endl;
}

signed main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int T=1;
	cin>>T;
	while(T--) solve();
}

B

.不会写，我是傻呗

#include <bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;

const int N = 2e5 + 10;
int c[N];

void solve(){
    int n;
    cin>>n;
    int ans=0;
    for(int i=1;i<=n;i++){
       cin>>c[i];
       ans+=max(0ll,c[i]-c[i-1]);
    }
    cout<<ans-1<<endl;
}

signed main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int T=1;
	cin>>T;
	while(T--) solve();
}

C

让最大值和最小值相等就行了。

#include <bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;

const int N = 2e5 + 10;
int a[N];
int n;

void solve(){
    cin>>n;
    for(int i=0;i<n;i++) cin>>a[i];
    int l=*min_element(a,a+n);
    int r=*max_element(a,a+n);
    vector<int> ans;
    while(l!=r){
        r = l + r >> 1;
        ans.push_back(l);
    }
    cout<<ans.size()<<endl;
    if(ans.size()<=n){
        for(auto u:ans) cout<<u<<" ";
        if(ans.size()) cout<<endl;
    }
}

signed main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int T=1;
	cin>>T;
	while(T--) solve();
}

D

感觉比B C简单，虽然我写半天

#include <bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;

const int N = 3e5 + 10;
int a[N];
int b[N],c[N];
int n;
void solve(){
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        b[i]=a[i]+n-i;
        c[i]=a[i]+i-1;
    }
    for(int i=1;i<=n;i++) b[i] = max(b[i],b[i-1]);
    for(int i=n;i>=1;i--) c[i] = max(c[i],c[i+1]);
    int ans=1e18;
    for(int i=1;i<=n;i++) ans=min(ans,max({a[i],b[i-1],c[i+1]}));
    cout<<ans<<endl;
}

signed main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int T=1;
	//cin>>T;
	while(T--) solve();
}