Codeforces Beta Round #7

Codeforces Beta Round #7

http://codeforces.com/contest/7

A

水题

#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 maxn 1000010
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */

string str[15];
int book[15][15];

int Check1(int x){//lie
    for(int i=0;i<8;i++){
        if(str[i][x]!='B') return 0;
    }
    int ans=0;
    for(int i=0;i<8;i++){
        if(book[i][x]==0) book[i][x]=1,ans=1;
    }
    return ans;
}

int Check2(int x){
    for(int i=0;i<8;i++){
        if(str[x][i]!='B') return 0;
    }
    int ans=0;
    for(int i=0;i<8;i++){
        if(book[x][i]==0) book[x][i]=1,ans=1;
    }
    return ans;
}


int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    for(int i=0;i<8;i++) cin>>str[i];
    int ans=0;
    for(int i=0;i<8;i++){
        ans+=Check1(i);
    }
    for(int i=0;i<8;i++){
        ans+=Check2(i);
    }
    cout<<ans<<endl;
}

B

模拟题

#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 maxn 1000010
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */

int t,n,m;
int book[105];
struct sair{
    int first,last;
    int flag,pos;
}a[105];

bool Check(int pos){
    int i;
    if(pos+n>m+1) return false;
    for(i=pos;i<pos+n;i++){
        if(book[i]){
            return false;
        }
    }
    return true;
}

bool cmp(sair a,sair b){
    if(a.flag==b.flag)
        return a.first<b.first;
    return a.flag>b.flag;
}

bool cmp2(sair a,sair b){
    return a.pos<b.pos;
}

int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    cin>>t>>m;
    string str;
    int co=1;
    int i;
    for(int i=1;i<=100;i++){
        a[i].flag=0;
        a[i].pos=i;
    }
    while(t--){
        cin>>str;
        if(str=="alloc"){
            cin>>n;
            for(i=1;i<=m;i++){
                if(Check(i)){
                  //  cout<<book[i]<<" "<<i<<"hhhhhhhhhhhhhhhhhhhhhhhhhhhhhh"<<endl;
                    a[co].first=i,a[co].last=i+n-1;
                    a[co].flag=1;
                 //   cout<<a[co].first<<" "<<a[co].last<<"hhhhhhhhhhhh"<<endl;
                    for(int j=a[co].first;j<=a[co].last;j++) book[j]=1;
                    cout<<co<<endl;
                    co++;
                    break;
                }
            }
            if(i==m+1){
                cout<<"NULL"<<endl;
            }
        }
        else if(str=="erase"){
            cin>>n;
            if(n<1||n>101){
                cout<<"ILLEGAL_ERASE_ARGUMENT"<<endl;
                continue;
            }
            if(a[n].flag==0){
                cout<<"ILLEGAL_ERASE_ARGUMENT"<<endl;
            }
            else{
                a[n].flag=0;
                for(i=a[n].first;i<=a[n].last;i++){
                    book[i]=0;
                }
            }
        }
        else{
            memset(book,0,sizeof(book));
            sort(a+1,a+co,cmp);
            int pos=1;
            for(i=1;i<co;i++){
                if(a[i].flag){
                    for(int j=a[i].first;j<=a[i].last;j++){
                        book[pos++]=1;
                    }
                    int tmp=a[i].last-a[i].first;
                    a[i].last=pos-1;
                    a[i].first=a[i].last-tmp;
                }
            }
            sort(a+1,a+co,cmp2);
        }
      //  for(int i=1;i<=3;i++) cout<<book[i]<<" hhhhhh"<<endl;
    }
}

C

扩展欧几里德模板题

#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 maxn 1000010
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */

void gcd(long long a,long long b,long long &d,long long &x,long long &y){
    if(!b){
        d=a;
        x=1;
        y=0;
    }
    else{
        gcd(b,a%b,d,y,x);
        y-=x*(a/b);
    }
}
int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    long long a,b,c,d,x,y;
    scanf("%lld%lld%lld",&a,&b,&c);
    gcd(a,b,d,x,y);
    if(c%d)
        printf("-1
");
    else
        printf("%lld %lld
",-x*c/d,-y*c/d);

}

D

字符串hash（好题）

思路：把字符串的前缀正着hash和倒着hash，比较hash值

#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 maxn 1000010
typedef long long ll;
/*#ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
#endif */

char str[5000005];
ll dp[5000005];
int main(){
    #ifndef ONLINE_JUDGE
        freopen("1.txt","r",stdin);
    #endif
    scanf("%s",str+1);
    ll ans=0;
    ll t1=0,w1=0,p=121,num=1;
    int len=strlen(str+1);
    for(int i=1;i<=len;i++){
        t1=t1*p+str[i];
        w1=num*str[i]+w1;
        num*=p;
        if(t1==w1){
            dp[i]=dp[i/2]+1;
            ans+=dp[i];
        }
    }
    printf("%lld
",ans);
}