AtCoder Grand Contest 030 自闭记

Posted 2021-01-30 gloid

　　A：阅读。

#include<iostream> 
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
#define ll long long
char getc(){char c=getchar();while ((c<‘A‘||c>‘Z‘)&&(c<‘a‘||c>‘z‘)&&(c<‘0‘||c>‘9‘)) c=getchar();return c;}
int gcd(int n,int m){return m==0?n:gcd(m,n%m);}
int read()
{
    int x=0,f=1;char c=getchar();
    while (c<‘0‘||c>‘9‘) {if (c==‘-‘) f=-1;c=getchar();}
    while (c>=‘0‘&&c<=‘9‘) x=(x<<1)+(x<<3)+(c^48),c=getchar();
    return x*f;
}
int a,b,c;
int main()
{
    a=read(),b=read(),c=read();
    cout<<b+min(c,a+b+1);
    return 0;
}

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　　B：一个显然的做法是设f[i][j][0/1]为已经砍掉了1~i和j~n的树且停在左/右边的最长路，类似区间dp转移即可。因为开始头铁想了会正解和初始化出了些锅，很久之后才过掉这个部分分。

#include<iostream> 
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
#define ll long long
#define N 200010
char getc(){char c=getchar();while ((c<‘A‘||c>‘Z‘)&&(c<‘a‘||c>‘z‘)&&(c<‘0‘||c>‘9‘)) c=getchar();return c;}
int gcd(int n,int m){return m==0?n:gcd(m,n%m);}
int read()
{
    int x=0,f=1;char c=getchar();
    while (c<‘0‘||c>‘9‘) {if (c==‘-‘) f=-1;c=getchar();}
    while (c>=‘0‘&&c<=‘9‘) x=(x<<1)+(x<<3)+(c^48),c=getchar();
    return x*f;
}
int n,m,a[N];
ll ans,f[2010][2010][2];
int main()
{
    m=read(),n=read();
    for (int i=1;i<=n;i++) a[i]=read();a[n+1]=m;
    memset(f,200,sizeof(f));
    f[1][n+1][0]=a[1],f[0][n][1]=m-a[n];
    for (int i=2;i<=n;i++)
        for (int j=0;j<=i;j++)
        {
            if (j) f[j][n+1-(i-j)][0]=max(f[j-1][n+1-(i-j)][0]+a[j]-a[j-1],f[j-1][n+1-(i-j)][1]+a[j]+m-a[n+1-(i-j)]);
            if (j<i) f[j][n+1-(i-j)][1]=max(f[j][n+2-(i-j)][1]+a[n+2-(i-j)]-a[n+1-(i-j)],f[j][n+2-(i-j)][0]+a[j]+m-a[n+1-(i-j)]);
        }
    for (int i=1;i<=n;i++) ans=max(ans,f[i][i+1][0]),ans=max(ans,f[i][i+1][1]);
    cout<<ans;
    return 0;
}

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　　然后因为一些原因也没什么心思想题，就这么心态平稳地自闭到结束了。根本没脸写这玩意了题过会再补

　　result：rank 312 rating +56 怎么打成什么样都涨分啊？