本文主要是介绍紫书训练 7.14,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
https://vjudge.net/contest/310985#overview 概率dp
密码:996996
A - Another Crisis
从大bose往下,按提交申请书人数从小到大排序,优先选择前面的即可,满足它选的那个比例即可。
#include<bits/stdc++.h>
#define il inline
#define pb push_back
#define fi first
#define se second
#define ms(_data,v) memset(_data,v,sizeof(_data))
#define sc(n) scanf("%d",&n)
#define SC(n,m) scanf("%d %d",&n,&m)
#define SZ(a) int((a).size())
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define drep(i,a,b) for(int i=a;i>=b;--i)
using namespace std;
typedef long long ll;
const ll inf=0x3f3f3f3f;
const double PI=acos(-1.0);
const double eps=1e-9;
const int maxn=1e5+5;
int n,T;
vector<int> son[maxn];
il int solve(int v){if(son[v].empty()) return 1;vector<int> ch;for(int i=0;i<SZ(son[v]);++i) ch.pb(solve(son[v][i]));sort(ch.begin(),ch.end());int len=SZ(ch),sum=0;int num=ceil((T*1.0)/100.0*len);for(int i=0;i<num;++i) sum+=ch[i];return sum;
}
int main(){std::ios::sync_with_stdio(0);while(cin>>n>>T && (n || T)){int x;rep(i,1,n){cin>>x;son[x].pb(i);} cout<<solve(0)<<endl;rep(i,0,n) son[i].clear();}return 0;
}
B - Minimax Triangulation
好鬼酷,这居然是区间dp,就是在转移的时候要judge一下,现在所选的3个点是不是将其他的点包在其中。
#include<bits/stdc++.h>
#define il inline
#define pb push_back
#define fi first
#define se second
#define ms(_data,v) memset(_data,v,sizeof(_data))
#define sc(n) scanf("%d",&n)
#define SC(n,m) scanf("%d %d",&n,&m)
#define SZ(a) int((a).size())
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define drep(i,a,b) for(int i=a;i>=b;--i)
using namespace std;
typedef long long ll;
const ll inf=0x3f3f3f3f;
const double PI=acos(-1.0);
const double eps=1e-9;
struct point {double x,y;
} p[60];
int n;
double dp[60][60];
double area(point a,point b,point c) {return abs((b.x-a.x)*(c.y-a.y)-(c.x-a.x)*(b.y-a.y))/2.0;
}
int judge(int a,int b,int c) {for(int i=0; i<n; ++i) {if(i!=a && i!=b && i!=c) {double tmp=area(p[a],p[b],p[i])+area(p[a],p[i],p[c])+area(p[i],p[b],p[c]);if(abs(tmp-area(p[a],p[b],p[c]))<eps) return false;}}return true;
}
void solve() {double ans=inf;for(int l=2; l<n; ++l)for(int i=0; i<n; ++i) {int j=(i+l)%n;dp[i][j]=inf;for(int k=(i+1)%n; k!=j; k=(k+1)%n) {if(judge(i,k,j)) {dp[i][j]=min(dp[i][j],max(max(dp[i][k],dp[k][j]),area(p[i],p[k],p[j])));}}if(l==n-1)ans=min(ans,dp[i][j]);}printf("%.1lf\n",ans);
}
int t;
int main() {
// std::ios::sync_with_stdio(0); scanf("%d",&t);while(t--) {scanf("%d",&n);for(int i=0; i<n; ++i) scanf("%lf%lf",&p[i].x,&p[i].y);solve();}return 0;
}
C - Polygon
代码很简单,但是结论的话,不看还真的想不到 可以参考一下,或者看紫薯
#include<bits/stdc++.h>
#define il inline
#define pb push_back
#define fi first
#define se second
#define ms(_data,v) memset(_data,v,sizeof(_data))
#define sc(n) scanf("%d",&n)
#define SC(n,m) scanf("%d %d",&n,&m)
#define SZ(a) int((a).size())
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define drep(i,a,b) for(int i=a;i>=b;--i)
using namespace std;
typedef long long ll;
const ll inf=0x3f3f3f3f;
const double PI=acos(-1.0);
const double eps=1e-9;
il ll gcd(ll a,ll b){return b==0?a:gcd(b,a%b);
}
int main(){int T;scanf("%d",&T);for(int kase=1;kase<=T;++kase){int n,k;scanf("%d%d",&n,&k);ll x=(1LL<<k)-(k+1);ll y=(1LL<<k);ll g=gcd(x,y);x/=g, y/=g;printf("Case #%d: %lld/%lld\n",kase,x,y);}return 0;
}
D - Headshot
一看图就被吓到了,计算几何吗?其实这个概率还是挺好算的,就是比较 连续两个无弹在总无弹之中的概率(因为前一个人无弹) 和 无弹在整个子弹个数中的概率 比较一下。
#include<bits/stdc++.h>
#define il inline
#define pb push_back
#define fi first
#define se second
#define ms(_data,v) memset(_data,v,sizeof(_data))
#define sc(n) scanf("%d",&n)
#define SC(n,m) scanf("%d %d",&n,&m)
#define SZ(a) int((a).size())
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define drep(i,a,b) for(int i=a;i>=b;--i)
using namespace std;
typedef long long ll;
const ll inf=0x3f3f3f3f;
const double PI=acos(-1.0);
const double eps=1e-9;
string s;
int main(){std::ios::sync_with_stdio(0);while(cin>>s){double all=0,two=0;int len=SZ(s);s.insert(s.end(),s[0]); rep(i,0,SZ(s)-2){if(s[i]=='0') all+=1.0;if(s[i+1]==s[i] && s[i]=='0') two+=1.0;}double p1=two/all,p2=all/(double)len;if(p1>p2) cout<<"SHOOT"<<endl;else if(p1==p2) cout<<"EQUAL"<<endl;else cout<<"ROTATE"<<endl; }return 0;
}
E - Probability|Given
看似dp,实则暴力,考虑买和不买的所有情况即可。
#include<bits/stdc++.h>
#define il inline
#define pb push_back
#define fi first
#define se second
#define ms(_data,v) memset(_data,v,sizeof(_data))
#define sc(n) scanf("%d",&n)
#define SC(n,m) scanf("%d %d",&n,&m)
#define SZ(a) int((a).size())
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define drep(i,a,b) for(int i=a;i>=b;--i)
using namespace std;
typedef long long ll;
const ll inf=0x3f3f3f3f;
const double PI=acos(-1.0);
const double eps=1e-9;
const int maxn=35;
double pi[maxn],a[maxn];
int n,r;
il double run(int num,double P,int numr){if(num == n+1){if(numr == r) return P;else return 0.0;}double p1=0,p2=0;if(numr < r){p1=run(num+1,P*a[num],numr+1);pi[num]+=p1;} p2=run(num+1,P*(1-a[num]),numr);return p1+p2;
}
int main(){std::ios::sync_with_stdio(0);int cnt=0;while(cin>>n>>r && (n || r)){rep(i,1,n) cin>>a[i];double all=run(1,1,0);printf("Case %d:\n", ++cnt);rep(i,1,n) printf("%.6lf\n",pi[i]/all);ms(pi,0);}return 0;
}
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