2019西北工业大学程序设计创新实践基地春季选拔赛(重现赛)补题笔记

A Chino with Geometry

#include <iostream>
#include <cmath>
#include <cstdio>
#include <algorithm>
using namespace std;
double dis(double x1,double y1,double x2,double y2)
{
return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
int main()
{
int ix0,iy0,ir,ix1,iy1,iy2;
cin >> ix0 >> iy0 >> ir >>ix1 >> iy1 >> iy2;
double x0 = (double)ix0,y0 = (double)iy0,r = (double)ir,x1 = (double)ix1,y1 = (double)iy1
,y2 = (double)iy2;
//printf("%lf %lf %lf %lf\n",y1,y2,x1,x0);
double k = (y1-y2)/x1;
double a=(1+k*k),b=(2*(y2-y0)*k-2*x0),c=x0*x0+(y2-y0)*(y2-y0)-r*r;
double dlta = b*b - 4*a*c;
double sx1 = (-b+sqrt(dlta))/(2*a),sx2 = (-b-sqrt(dlta))/(2*a);
double sy1 = k*sx1 + y2 ,sy2 = k*sx2 + y2;
//printf("%lf %lf %lf %lf\n",k,sy1,sx2,sy2);
cout << (long long)(dis(sx1,sy1,x1,y1)*dis(sx2,sy2,x1,y1)+0.5) << endl;
return 0;
}

B Chino with Repeater

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
int n;
cin >> n;
int t = log(n)/log(2);
if(n==(1<<t))cout << t << endl;
else cout << t+1 << endl;
return 0;
}

D Chino with Equation

#include <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;
const ll mod = 1e9+7;
ll exgcd(ll a,ll b,ll& x,ll& y){
if(a%b==0){
x=0,y=1;
return b;
}
ll r,tx,ty;
r=exgcd(b,a%b,tx,ty);
x=ty;
y=tx-a/b*ty;
return 0;
}

ll comp(ll a,ll b,ll m){
if(a<b) return 0;
if(a==b) return 1;
if(b>a-b) b=a-b;
ll ans=1,ca=1,cb=1;
for(int i=0;i<b;i++){
ca=ca*(a-i)%m;
cb=cb*(b-i)%m;
}
ll x,y;
exgcd(cb,m,x,y);
x=(x%mod+mod)%m;
ans=ca*x%m;
return ans;
}

ll lucas(ll a,ll b,ll m){
ll ans=1;
while(a&&b){
ans=(ans*comp(a%m,b%m,m))%m;
a/=m;
b/=m;
}
return ans;
}
int main()
{
ll m,n;
cin >> m >> n ;
cout << lucas(n-1,m-1,mod) << ' ' << lucas(m+n-1,m-1,mod) << endl;
return 0;
}

F Chino with Expectation

#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;
const int N = 1e5+10;
int a
={0};
int main()
{
int n,q;
scanf("%d%d",&n,&q);
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
a[i]+=a[i-1];
}
while(q--)
{
int x,l,r;
scanf("%d%d%d",&x,&l,&r);
double ans = a[r]-a[l-1];
double p = (r-l+1)/(double)n;
printf("%.6lf\n",ans/(r-l+1)*(1-p)+(ans+x)/(r-l+1)*(p));
}
return 0;
}

G Chino with Train to the Rabbit Town

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
using namespace std;
const int N =5e5+10;
int w
,dp
={0},pre
;
int main()
{
int n,k,mx=0;
scanf("%d%d",&n,&k);
memset(pre,-1,sizeof(pre));
dp[0]=w[0]=pre[0]=0;
for(int i=1;i<=n;i++)
{
scanf("%d",&w[i]);
w[i]^=w[i-1];
dp[i]=dp[i-1];
if(pre[w[i]^k]!=-1)
dp[i]=max(dp[i],dp[pre[w[i]^k]]+1);
mx=max(mx,dp[i]);
pre[w[i]]=i;
}
printf("%d\n",mx);
return 0;
}

H Chino with Ciste

#include <iostream>
#include <algorithm>
#include <queue>
#include <cstdio>
#include <cstring>
using namespace std;
typedef pair<int,int> PII;
const int N =2e3+10;
struct s
{
int x,y,step,turns,d;
s(int _x,int _y,int _s,int _t,int _d):x(_x),y(_y),step(_s),turns(_t),d(_d){}
bool operator < (const s &a) const
{
if(a.turns!=turns)return a.turns < turns;
else return a.step < step;
}
};
char mp

;
int ans=0,vis

;
pair<int,int>dir[4]={{1,0},{-1,0},{0,1},{0,-1}};
priority_queue <s> q;
PII S,E;
int n,m;
int bfs()
{
int flag=1;
while(!q.empty())q.pop();
q.push(s(S.first,S.second,0,0,0));
vis[S.first][S.second]=1;
while(!q.empty())
{
s z = q.top();
q.pop();
//cout << z.x << " " << z.y << " " << z.d << endl;
if(z.x==E.first&&z.y==E.second)
{
printf("%d\n",z.turns);
flag=0;
return 0;
}
for(int i=0;i<4;i++)
{
int x1=z.x+dir[i].first,y1 = z.y+dir[i].second;
if(x1>=0&&x1<n&&y1>=0&&y1<m&&(!vis[x1][y1])&&mp[x1][y1]!='*')
{
vis[z.x][z.y]=1;
if(z.d==0)
{
if(i<2)q.push(s(x1,y1,z.step+1,z.turns,1));
else q.push(s(x1,y1,z.step+1,z.turns,2));
}
else if(i<2)
{
if(z.d==1)q.push(s(x1,y1,z.step+1,z.turns,1));
else q.push(s(x1,y1,z.step+1,z.turns+1,1));
}
else
{
if(z.d==1)q.push(s(x1,y1,z.step+1,z.turns+1,2));
else q.push(s(x1,y1,z.step+1,z.turns,2));
}
}
}
}
if(flag)printf("troil\n");
return 0;
}
int main()
{
memset(vis,0,sizeof(vis));
scanf("%d%d",&n,&m);
getchar();
for(int i=0;i<n;i++)
for(int j=0;j<=m;j++)
{
mp[i][j]=getchar();
if(mp[i][j]=='S')S = {i,j};
if(mp[i][j]=='T')E = {i,j};
}
//printf("%d %d %d %d \n",S.first,S.second,E.first,E.second);
bfs();
return 0;
}

C Chino with Queue

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
using namespace std;
int n;
struct ios {
inline char read(){
static const int IN_LEN=1<<18|1;
static char buf[IN_LEN],*s,*t;
return (s==t)&&(t=(s=buf)+fread(buf,1,IN_LEN,stdin)),s==t?-1:*s++;
}

template <typename _Tp> inline ios & operator >> (_Tp&x){
static char c11,boo;
for(c11=read(),boo=0;!isdigit(c11);c11=read()){
if(c11==-1)return *this;
boo|=c11=='-';
}
for(x=0;isdigit(c11);c11=read())x=x*10+(c11^'0');
boo&&(x=-x);
return *this;
}
} io;
const int N=20;
int w

,dp
[1<<N];
int slove()
{
for(int i=0;i<n;i++)dp[i][1<<i]=w[i][i];
for(int i=1;i<(1<<n);++i)
for(int j=0;j<n;++j)
for(int k=0;k<n;++k)
{
if(((i&(1<<j))==0)&&(i&(1<<k)))
{
dp[j][i|(1<<j)]=max(dp[j][i|(1<<j)],dp[k][i]+w[j][k]);
}
}
int mx=0;
for(int i=0;i<n;i++)mx = max(dp[i][(1<<n)-1],mx);
return mx;
}
int main()
{
scanf("%d",&n);
for(int i=0;i<n;i++)
for(int j=0;j<n;j++)
io >> w[i][j];
printf("%d",slove());
return 0;
}