Codeforces Beta Round #54 (Div. 2)

Codeforces Beta Round #54 (Div. 2)

http://codeforces.com/contest/58

A

找子序列

#include<bits/stdc++.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define sqr(x) ((x)*(x))
#define pb push_back
#define eb emplace_back
#define maxn 1000005
#define rep(k,i,j) for(int k=i;k<j;k++)
typedef long long ll;
typedef unsigned long long ull;


int main(){
    #ifndef ONLINE_JUDGE
       // freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    string str;
    string s="hello";
    cin>>str;
    int i=0,j=0;
    while(i<s.length()&&j<str.length()){
        if(s[i]==str[j]){
            i++,j++;
        }
        else{
            j++;
        }
    }
    if(i==s.length()){
        cout<<"YES"<<endl;
    }
    else cout<<"NO"<<endl;
}

B

#include<bits/stdc++.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define sqr(x) ((x)*(x))
#define pb push_back
#define eb emplace_back
#define maxn 1000005
#define rep(k,i,j) for(int k=i;k<j;k++)
typedef long long ll;
typedef unsigned long long ull;


int main(){
    #ifndef ONLINE_JUDGE
       // freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    int n;
    cin>>n;
    for(int i=n;i>=1;i--){
        if(n%i==0){
            cout<<i<<" ";
            n=i;
        }
    }
}

C

逆向思维，求出最多不需要修改的数量，然后减去它即可

#include<bits/stdc++.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define sqr(x) ((x)*(x))
#define pb push_back
#define eb emplace_back
#define maxn 1000005
#define rep(k,i,j) for(int k=i;k<j;k++)
typedef long long ll;
typedef unsigned long long ull;

int n;
int a[100005];

int main(){
    #ifndef ONLINE_JUDGE
       // freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    cin>>n;
    int m;
    int ans=0;
    for(int i=1;i<=n;i++){
        cin>>m;
        int num=min(i,n-i+1);
        m-=num;
        if(m>=0){
            a[m]++;
            ans=max(ans,a[m]);
        }
    }
    cout<<n-ans<<endl;

}

D

在每个字符串后面加上字符d，然后sort+贪心即可

#include<bits/stdc++.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define sqr(x) ((x)*(x))
#define pb push_back
#define eb emplace_back
#define maxn 1000005
#define rep(k,i,j) for(int k=i;k<j;k++)
typedef long long ll;
typedef unsigned long long ull;

int n;
string str[20004];
int book[20004];
string ans[20004];
string d;

int main(){
    #ifndef ONLINE_JUDGE
       // freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    cin>>n;
    int sum=0;
    for(int i=1;i<=n;i++){
        cin>>str[i];
        sum+=str[i].length();
    }
    cin>>d;
    for(int i=1;i<=n;i++){
        str[i]+=d;
    }
    sum+=n/2;
    int len=sum/(n/2);
    int co=1;
    sort(str+1,str+n+1);
    for(int i=1;i<=n;i++){
        if(!book[i]){
            ans[co]=str[i];
            book[i]=1;
            for(int j=1;j<=n;j++){
                if(!book[j]&&str[i].length()-1+str[j].length()==len){
                    ans[co]+=str[j].substr(0,str[j].length()-1);
                    book[j]=1;
                    co++;
                    break;
                }
            }
        }
    }
    for(int i=1;i<co;i++){
        cout<<ans[i]<<endl;
    }
}

E

搜索

#include<bits/stdc++.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define sqr(x) ((x)*(x))
#define pb push_back
#define eb emplace_back
#define maxn 1000005
#define rep(k,i,j) for(int k=i;k<j;k++)
typedef long long ll;
typedef unsigned long long ull;

ll ans1,ans2;
ll p[15];
ll ans=13;
void dfs(ll a,ll b,ll c,ll ra,ll rb, ll jw, ll inc,ll d){
    if(inc>=ans) return;
    if(!a&&!b&&!c&&!jw){
        ans=inc;ans1=ra;ans2=rb;return;
    }
    if(!c){
        ll s=a+b+jw;
        int k=0;
        while(s){
            s/=10;
            k++;
        }
        dfs(0,0,0,a*p[d]+ra,b*p[d]+rb,0,inc+k,d);
        return;
    }
    if((a+b+jw)%10==c%10){
        dfs(a/10,b/10,c/10,a%10*p[d]+ra,b%10*p[d]+rb,(a%10+b%10+jw)/10,inc,d+1);
    }
    else{
        dfs(a*10+(c+10-b%10-jw)%10,b,c,ra,rb,jw,inc+1,d);
        dfs(a,b*10+(c+10-a%10-jw)%10,c,ra,rb,jw,inc+1,d);
        dfs(a,b,c*10+(a+b+jw)%10,ra,rb,jw,inc+1,d);
    }
}


int main(){
    #ifndef ONLINE_JUDGE
       // freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    ll a,b,c;
    char ch;
    cin>>a>>ch>>b>>ch>>c;
    p[0]=1;
    for(int i=1;i<=13;i++) p[i]=p[i-1]*10;
    dfs(a,b,c,0,0,0,0,0);
    cout<<ans1<<"+"<<ans2<<"="<<ans1+ans2<<endl;
}