A B题用python

A

1576

B

781448427

C

打表找规律

#include<bits/stdc++.h>
bool fun(int n)
{
    for(int i=-100;i<=100;++i)
    {
        int sum=0;
        for(int j=i;j<=200;++j)
        {
            sum+=j;
            if(j-i>3&&sum==n) return 1;
        }

    }
    return 0;
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
    {
        if(fun(i)) printf("%d:yes\n",i);
        else printf("%d:no\n",i);
    }
    return 0;
}

写完上面也能想到怎么证明了

提交：

#include<bits/stdc++.h>
int main()
{
    int n,ans=0;
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
    {
        int x;
        scanf("%d",&x);
        if(x>=2) ++ans;
    }
    printf("%d\n",ans);
    return 0;
}

洛谷评测：100

D

#include<bits/stdc++.h>
typedef long long LL;
void fun(LL a,LL b,LL c,LL k)
{
    for(int i=1;i<=k;++i)
    {
        int ta=b+c>>1;
        int tb=a+c>>1;
        int tc=a+b>>1;
        if(ta==a&&tb==b&&tc==c) break;
        a=ta;
        b=tb;
        c=tc;
    }
    printf("%lld %lld %lld\n",a,b,c);
}

int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        LL a,b,c,k;
        scanf("%lld%lld%lld%lld",&a,&b,&c,&k);
        fun(a,b,c,k);
    }
    return 0;
}

/*
int main()
{
    for(int i=0;i<=100;++i)
    {
        printf("k=%d:",i);
        fun(100,200,300,i);
    }
    return 0;
}
*/
/*
int main()
{
    for(int i=1;i<=100000;++i)
    {
        fun(1,1,1000000000,1000000000);
    }
    return 0;
}
*/

应该不会TLE，洛谷100分

E

#include<bits/stdc++.h>
using std::sort;
using std::min;
typedef long long LL;
const int N=1e5+10;
const LL INF=0x3f3f3f3f3f3f3f3f;
LL arr[N],t[N],s[N];//t[i] presents abs(arr[i]*arr[i]-arr[i-1]*arr[i-1])
LL abs(LL x)
{
    return x>0?x:-x;
}
LL getL(int l,int r)//from [l,r] get L
{
    LL ans=0;
    for(int i=l+1;i<=r;++i) ans+=abs(arr[i]*arr[i]-arr[i-1]*arr[i-1]);
    return ans;
}
void fun()
{
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;++i) scanf("%lld",&arr[i]);
    sort(arr+1,arr+n+1);
    for(int i=2;i<=n;++i)
    {
        t[i]=abs(arr[i]*arr[i]-arr[i-1]*arr[i-1]);
        s[i]=s[i-1]+t[i];//s[i] presents sum of t[i]
        //printf("%d ",s[i]);
    }
    LL ans=INF;
    for(int i=1;i+m-1<=n;++i)
        // cal the ans from i to i-m+1
        ans=min(ans,s[i+m-1]-s[i]);
    printf("%lld\n",ans);
}
int main()
{
    fun();
    return 0;
}


//ex:4 2 1 2 4 5

//ex:10 5 1 2 3 4 5 6 7 8 9 10

//ex:10 5 1 34 35 36 37 38 39 40 41 42

E本地测试

#include<bits/stdc++.h>
using std::sort;
using std::min;
typedef long long LL;
const int N=1e5+10;
const LL INF=0x3f3f3f3f3f3f3f3f;
LL arr[N],t[N];//t[i] presents abs(arr[i]*arr[i]-arr[i-1]*arr[i-1])
LL abs(LL x)
{
    return x>0?x:-x;
}
LL getL(int l,int r)//from [l,r] get L
{
    LL ans=0;
    for(int i=l+1;i<=r;++i) ans+=abs(arr[i]*arr[i]-arr[i-1]*arr[i-1]);
    return ans;
}
void fun()
{
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;++i) scanf("%lld",&arr[i]);
    sort(arr+1,arr+n+1);
    LL ans=INF;
    for(int i=1;i+m-1<=n;++i)
    {   
        ans=min(ans,getL(i,i+m-1));
    }
    for(int i=1;i+m-1<=n;++i)
    {
        if(ans==getL(i,i+m-1))
        {
            for(int j=i;j<=i+m-1;++j)
            {
                printf("%lld ",arr[j]);
            }
            printf("\n");
            return;
        }
    }
}
int main()
{
    fun();
    return 0;
}


//ex:4 2 1 2 4 5

//ex:10 5 1 2 3 4 5 6 7 8 9 10

//ex:10 5 1 34 35 36 37 38 39 40 41 42

洛谷CE了，abs不是std::abs，dev正常。直接冲突编译错误，希望蓝桥杯的测试环境也是windows吧，如果是linux我就完蛋了

如果改掉CE是100

F

应该是不难的dp

#include<bits/stdc++.h>
using std::string;
using std::cin;
using std::cout;
using std::endl;
const int N=1e6+10;
int dp[N];
bool check(int casecheck,char a,char b,char c,char d)
{
    switch(casecheck)
    {
        case 1:if(a=='#'&&b=='.'&&c=='.'&&d=='#') return 1;else return 0;break;
        case 2:if(a=='#'&&b=='.'&&c=='#'&&d=='.') return 1;else return 0;break;
        case 3:if(a=='#'&&b=='.'&&c=='.'&&d=='.') return 1;else return 0;break;
        case 4:if(a=='.'&&b=='.'&&c=='#'&&d=='.') return 1;else return 0;break;
        case 5:if(a=='.'&&b=='#'&&c=='#'&&d=='.') return 1;else return 0;break;
        default:return 0;
    }
}
int main()
{
    string str1,str2;
    cin>>str1>>str2;
    int index=0;
    for(;str1[index]=='.'&&str2[index]=='.';++index);
    for(int i=str1.length()-1;str1[i]=='.'&&str2[i]=='.';--i) str1[i]=str2[i]='#';
    //cout<<str1<<endl<<str2<<endl;
    //next we start dp
    for(++index;index<str1.length();++index)
    {
        //case1:#..#
        if(check(1,str1[index-1],str1[index],str2[index-1],str2[index]))
        {
            dp[index]=dp[index-1]+1;
            str1[index]='#';
        }
        else if(check(2,str1[index-1],str1[index],str2[index-1],str2[index]))
        {
            dp[index]=dp[index-1]+1;
            str1[index]='#';
            str2[index]='#';
        }
        else if(check(3,str1[index-1],str1[index],str2[index-1],str2[index]))
        {
            dp[index]=dp[index-1]+1;
            str1[index]='#';
        }
        else if(check(4,str1[index-1],str1[index],str2[index-1],str2[index]))
        {
            dp[index]=dp[index-1]+1;
            str2[index]='#';
        }
        else if(check(5,str1[index-1],str1[index],str2[index-1],str2[index]))
        {
            dp[index]=dp[index-1]+1;
            str2[index]='#';
        }
        else
        {
            dp[index]=dp[index-1];
            //cout<<"case default"<<endl;
        }
    }
    //cout<<str1<<endl<<str2<<endl;
    printf("%lld\n",dp[str1.length()-1]);
    return 0;
}


/*
eg;
.##.....#
.#.#.#...
5

.##......
.#.#.#...
2
*/

洛谷100

G

#include<bits/stdc++.h>
using std::vector;
using std::cout;
using std::endl;
using std::max;
using std::min;
using std::unordered_set;
typedef long long LL;
const int N=2e5+10,M=1e6+10;
int e[2*N],ne[2*N],h[2*N],idx=1,w[N],n,dp[M],du[N];
bool st[N];
void add(int a,int b)
{
    e[idx]=b;
    ne[idx]=h[a];
    h[a]=idx++;
}
int dfs(int node)
{
    vector<int>vec;
    if(st[node]) return w[node];
    st[node]=1;
    for(int i=h[node];i;i=ne[i])
    {
        vec.push_back(dfs(e[i])); 
    }
    if(vec.size()==0)
    {
        //cout<<"node"<<node<<"returned"<<endl;
        return w[node];
    }
    //dp


    /*debug
    cout<<"node:"<<node<<":";
    for(auto x:vec) printf("%d ",x);
    cout<<endl;
    */



    memset(dp,0,sizeof dp);
    for(int i=0;i<vec.size();++i)//第i样东西的价值为vec[i] 
    {
        for(int j=w[node];j>=0&&j>=vec[i];--j)
        {
            if(dp[j-vec[i]]+vec[i]>=dp[j])
            {
                dp[j]=dp[j-vec[i]]+vec[i];
            }
        }
    }

    return dp[w[node]];
}
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;++i) scanf("%d",&w[i]);
    for(int i=1;i<=n-1;++i)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        add(a,b);
        add(b,a);
        ++du[a];
        ++du[b];
    }
    if(n==2) printf("%d\n",min(w[0],w[1]));
    else if(n==3)
    {
        if(du[1]==1) printf("%d\n",min(w[1],w[2],w[3]));
        else if(du[1]==2) printf("%d\n",min(w[1],max(min(w[1],w[2]+w[3]),w[2],w[3])));
    }
    else printf("%d\n",dfs(1));
    return 0;
}

/*

9
9 7 3 7 1 6 2 2 7
1 2
1 3
2 4
2 5
2 6
6 7
6 8
6 9
*/

*/

这题也CE了，因为vector没有length方法，只有size，代码其他地方其实我都写的size，不知道怎么脑子一抽写了length

如果修了CE 洛谷55分

H

洛谷橙色，但我觉得不难

#include<bits/stdc++.h>
typedef long long LL;
const int N=1e5+10;
const int MOD=1e9+7;
LL arr[N],n,t[N],xornum[N];//t[N] qkpans xornum[i] presents sor of nums 
LL qkp(LL a,LL b,LL c) //a^b%c
{
    LL t=a;
    a=1;
    while(b)
    {
        if(b&1) a=a*t%c;
        t=t*t%c;
        b>>=1;
    }
    return a;
}
int main()
{
    scanf("%lld",&n);
    t[0]=1;
    for(int i=1;i<=n;++i) t[i]=t[i-1]*3%MOD;
    //for(int i=1;i<=n;++i) printf("%lld ",t[i]);
    for(int i=1;i<=n;++i)
    {
        scanf("%lld",&arr[i]);
        if(i==1) xornum[i]=arr[i];
        else xornum[i]=xornum[i-1]^arr[i];
        //printf("%lld ",xornum[i]);
    }
    LL ans=0;
    for(int i=1,j=n-1;i<=n;++i,--j)
    {
        ans=(ans+(t[j]-t[j-1])*xornum[i])%MOD;
        //printf("%lld\n",ans);
    }
    printf("%lld\n",ans);
    return 0;
}

洛谷100