Codeforces Beta Round #7

http://codeforces.com/contest/7

A

水题

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define lson l,mid,rt<<1
 4 #define rson mid+1,r,rt<<1|1
 5 #define sqr(x) ((x)*(x))
 6 #define maxn 1000010
 7 typedef long long ll;
 8 /*#ifndef ONLINE_JUDGE
 9         freopen("1.txt","r",stdin);
10 #endif */
11
12 string str[15];
13 int book[15][15];
14
15 int Check1(int x){//lie
16     for(int i=0;i<8;i++){
17         if(str[i][x]!=‘B‘) return 0;
18     }
19     int ans=0;
20     for(int i=0;i<8;i++){
21         if(book[i][x]==0) book[i][x]=1,ans=1;
22     }
23     return ans;
24 }
25
26 int Check2(int x){
27     for(int i=0;i<8;i++){
28         if(str[x][i]!=‘B‘) return 0;
29     }
30     int ans=0;
31     for(int i=0;i<8;i++){
32         if(book[x][i]==0) book[x][i]=1,ans=1;
33     }
34     return ans;
35 }
36
37
38 int main(){
39     #ifndef ONLINE_JUDGE
40         freopen("1.txt","r",stdin);
41     #endif
42     std::ios::sync_with_stdio(false);
43     for(int i=0;i<8;i++) cin>>str[i];
44     int ans=0;
45     for(int i=0;i<8;i++){
46         ans+=Check1(i);
47     }
48     for(int i=0;i<8;i++){
49         ans+=Check2(i);
50     }
51     cout<<ans<<endl;
52 }

B

模拟题

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 #define lson l,mid,rt<<1
  4 #define rson mid+1,r,rt<<1|1
  5 #define sqr(x) ((x)*(x))
  6 #define maxn 1000010
  7 typedef long long ll;
  8 /*#ifndef ONLINE_JUDGE
  9         freopen("1.txt","r",stdin);
 10 #endif */
 11
 12 int t,n,m;
 13 int book[105];
 14 struct sair{
 15     int first,last;
 16     int flag,pos;
 17 }a[105];
 18
 19 bool Check(int pos){
 20     int i;
 21     if(pos+n>m+1) return false;
 22     for(i=pos;i<pos+n;i++){
 23         if(book[i]){
 24             return false;
 25         }
 26     }
 27     return true;
 28 }
 29
 30 bool cmp(sair a,sair b){
 31     if(a.flag==b.flag)
 32         return a.first<b.first;
 33     return a.flag>b.flag;
 34 }
 35
 36 bool cmp2(sair a,sair b){
 37     return a.pos<b.pos;
 38 }
 39
 40 int main(){
 41     #ifndef ONLINE_JUDGE
 42         freopen("1.txt","r",stdin);
 43     #endif
 44     std::ios::sync_with_stdio(false);
 45     cin>>t>>m;
 46     string str;
 47     int co=1;
 48     int i;
 49     for(int i=1;i<=100;i++){
 50         a[i].flag=0;
 51         a[i].pos=i;
 52     }
 53     while(t--){
 54         cin>>str;
 55         if(str=="alloc"){
 56             cin>>n;
 57             for(i=1;i<=m;i++){
 58                 if(Check(i)){
 59                   //  cout<<book[i]<<" "<<i<<"hhhhhhhhhhhhhhhhhhhhhhhhhhhhhh"<<endl;
 60                     a[co].first=i,a[co].last=i+n-1;
 61                     a[co].flag=1;
 62                  //   cout<<a[co].first<<" "<<a[co].last<<"hhhhhhhhhhhh"<<endl;
 63                     for(int j=a[co].first;j<=a[co].last;j++) book[j]=1;
 64                     cout<<co<<endl;
 65                     co++;
 66                     break;
 67                 }
 68             }
 69             if(i==m+1){
 70                 cout<<"NULL"<<endl;
 71             }
 72         }
 73         else if(str=="erase"){
 74             cin>>n;
 75             if(n<1||n>101){
 76                 cout<<"ILLEGAL_ERASE_ARGUMENT"<<endl;
 77                 continue;
 78             }
 79             if(a[n].flag==0){
 80                 cout<<"ILLEGAL_ERASE_ARGUMENT"<<endl;
 81             }
 82             else{
 83                 a[n].flag=0;
 84                 for(i=a[n].first;i<=a[n].last;i++){
 85                     book[i]=0;
 86                 }
 87             }
 88         }
 89         else{
 90             memset(book,0,sizeof(book));
 91             sort(a+1,a+co,cmp);
 92             int pos=1;
 93             for(i=1;i<co;i++){
 94                 if(a[i].flag){
 95                     for(int j=a[i].first;j<=a[i].last;j++){
 96                         book[pos++]=1;
 97                     }
 98                     int tmp=a[i].last-a[i].first;
 99                     a[i].last=pos-1;
100                     a[i].first=a[i].last-tmp;
101                 }
102             }
103             sort(a+1,a+co,cmp2);
104         }
105       //  for(int i=1;i<=3;i++) cout<<book[i]<<" hhhhhh"<<endl;
106     }
107 }

C

扩展欧几里德模板题

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define lson l,mid,rt<<1
 4 #define rson mid+1,r,rt<<1|1
 5 #define sqr(x) ((x)*(x))
 6 #define maxn 1000010
 7 typedef long long ll;
 8 /*#ifndef ONLINE_JUDGE
 9         freopen("1.txt","r",stdin);
10 #endif */
11
12 void gcd(long long a,long long b,long long &d,long long &x,long long &y){
13     if(!b){
14         d=a;
15         x=1;
16         y=0;
17     }
18     else{
19         gcd(b,a%b,d,y,x);
20         y-=x*(a/b);
21     }
22 }
23 int main(){
24     #ifndef ONLINE_JUDGE
25         freopen("1.txt","r",stdin);
26     #endif
27     long long a,b,c,d,x,y;
28     scanf("%lld%lld%lld",&a,&b,&c);
29     gcd(a,b,d,x,y);
30     if(c%d)
31         printf("-1\n");
32     else
33         printf("%lld %lld\n",-x*c/d,-y*c/d);
34
35 }

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

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define lson l,mid,rt<<1
 4 #define rson mid+1,r,rt<<1|1
 5 #define sqr(x) ((x)*(x))
 6 #define maxn 1000010
 7 typedef long long ll;
 8 /*#ifndef ONLINE_JUDGE
 9         freopen("1.txt","r",stdin);
10 #endif */
11
12 char str[5000005];
13 ll dp[5000005];
14 int main(){
15     #ifndef ONLINE_JUDGE
16         freopen("1.txt","r",stdin);
17     #endif
18     scanf("%s",str+1);
19     ll ans=0;
20     ll t1=0,w1=0,p=121,num=1;
21     int len=strlen(str+1);
22     for(int i=1;i<=len;i++){
23         t1=t1*p+str[i];
24         w1=num*str[i]+w1;
25         num*=p;
26         if(t1==w1){
27             dp[i]=dp[i/2]+1;
28             ans+=dp[i];
29         }
30     }
31     printf("%lld\n",ans);
32 }

E（待补）

原文地址：https://www.cnblogs.com/Fighting-sh/p/10350698.html