Summer training round2 #1

A:水

B:求两个三角形之间的位置关系:相交 相离 内含

①用三个点是否在三角形内外判断    计算MA*MB、MB*MC、MC*MA的大小 若这三个值同号，那么在三角形的内部，异号在外部

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#define INF 2139062143
#define inf -2139062144
#define ll long long
using namespace std;
int x[],y[];
int dian(int a,int i,int j) {
    return (x[a] - x[i])*(x[a]-x[j]) + (y[a] - y[i]) * (y[a] - y[j]);
}
bool pan(int a,int b,int c) {
    int zheng = ,fu = ;
    if(a>)    zheng++;
    if(b>)    zheng++;
    if(c>)    zheng++;
    fu =  - zheng;
    if(fu ==  || fu == )    return true;
    else    return false;
}
int main() {
    int t;
    int i;
    scanf("%d",&t);
    bool xx[];
    while(t--) {
        for(i=; i<; i++) {
            scanf("%d%d",&x[i],&y[i]);
        }
        for(i=; i<; i++) {
            xx[i] = pan(dian(i,,),dian(i,,),dian(i,,));
//            printf("fuck:%d %d %d\n",dian(i,3,4),dian(i,4,5),dian(i,3,5));
        }
        for(i=; i<; i++) {
            xx[i] = pan(dian(i,,),dian(i,,),dian(i,,));
//            printf("fuck:%d %d %d\n",dian(i,0,1),dian(i,0,2),dian(i,1,2));
        }
//        for(i=0; i<6; i++)    printf("%d ",xx[i]);
        if(xx[] == true && xx[] == true && xx[] == true) {
            printf("contain\n");
            continue;
        }
        if(xx[] == true && xx[] == true && xx[] == true) {
            printf("contain\n");
            continue;
        }
        if(xx[] == false && xx[] == false && xx[] == false && xx[] == false && xx[] == false && xx[] == false) {
            printf("disjoint\n");
            continue;
        }
        printf("intersect\n");
    }
    return ;
}

D:KMP加上特殊情况判断

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#define INF 2139062143
#define inf -2139062144
#define MOD 1000000007
#define mem(a,b) memset((a),b,sizeof(a))
#define TS printf("!!!\n")
#define pb push_back
#define pai pair<int,int>
using namespace std;
string ori,pat;
int n,nxt[],ans=;
int GetNext()
{
    nxt[]=nxt[]=;
    for(int i=;i<pat.size();i++)
    {
        int j=nxt[i];
        while(j&&pat[i]!=pat[j])j=nxt[j];
        nxt[i+]=((pat[i]==pat[j])?j+:);
    }
}
int Kmp()
{
    memset(nxt,,sizeof(nxt));
    GetNext();
    int j=;
    for(int i=;i<ori.size();i++)
    {
        while(j&&ori[i]!=pat[j])j=nxt[j];
        if(ori[i]==pat[j])j++;
        if(j==pat.size())ans++;
    }
}
int main()
{
    scanf("%d",&n);
    for(int i=;i<=n;i++)
    {
        cin>>ori>>pat;
        if(pat.size()>ori.size())
        {
            cout<<"Bob"<<endl;
        }else
        {
            int flag1=,flag2=;
            ans=;Kmp();
            if(ans)flag1=;
            reverse(pat.begin(),pat.end());
            string t="";
            int j;
            for(j=;j<pat.size();j++)
            {
                if(pat[j]!='')break;
            }
            for(;j<pat.size();j++)
            {
                t+=pat[j];
            }
            pat=t;
            ans=;Kmp();
            if(ans)flag2=;
            if(flag1||flag2)cout<<"Alice"<<endl;else cout<<"Bob"<<endl;
        }
    }
    return ;
}

G:猜公式(JAVA)

import java.math.BigInteger;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        int t;
        Scanner input = new Scanner(System.in);
        t = input.nextInt();
        while (t-- > ) {
//           BigInteger n = input.nextBigInteger();
            int n = input.nextInt();
            BigInteger flag = BigInteger.valueOf();
           for(int i = ;i<=n;i++){
                    flag = flag.multiply(BigInteger.valueOf(i));
           }
           BigInteger ans = BigInteger.valueOf();
            for(int i = ;i<=n;i++){
               ans = ans.add(flag.divide(BigInteger.valueOf(i)));
            }
            System.out.println(ans + ".0");
        }
    }
}

F:DFS序加树状数组  子节点增加的值为x+dep[v]∗k−dep[s]∗k,那么维护两个值x+dep[v]*k与-k,用两个树状数组维护这两个值，做到区间修改，单点查询

I:哈希加暴力 或者直接用strcmp函数判

K:错排加逆元加快速幂

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#define INF 2139062143
#define inf -2139062144
#define MOD 1000000007
#define mem(a,b) memset((a),b,sizeof(a))
#define TS printf("!!!\n")
#define pb push_back
#define pai pair<int,int>
//using ll = long long;
//using ull= unsigned long long;
//std::ios::sync_with_stdio(false);
using namespace std;
//priority_queue<int,vector<int>,greater<int>> que;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pai1;
const double EPS=1e-;
const double PI=acos(-);
ll mod=;
const int maxn=;
ll cuo[maxn];
ll ni[maxn];
ll jie[maxn];
ll quick_pow(ll a,ll n)
{
    ll result=;
    while(n>)
    {
        if(n&)
        result=(result*a)%mod;
        a=(a*a)%mod;
        n/=;
    }
    return result;
}
void init()
{
 cuo[]=;
 cuo[]=;
 for(int i=;i<=;i++)
 cuo[i]=(i-)*(cuo[i-]+cuo[i-])%mod;
 ni[]=jie[]=;
 jie[]=ni[]=ni[]=jie[]=;
 for(int i=;i<=;i++)
 {
  jie[i]=i*jie[i-]%mod;
  ni[i]=quick_pow(jie[i],mod-);
 }
}
int main()
{
   //freopen("input.txt","r",stdin);
   //freopen("out.txt","w",stdout);
   init();
   int t;
    cin>>t ;
    ll anser=;
    while(t--)
    {
        anser=;
        int n,k;
        cin >> n >> k;
        int now=n-k;
        if(now==||now==)
        {
        if(now==)
        {
        printf("1\n");
        continue;
        }
        else
        {
        printf("0\n");
        continue;
        }
        }
        anser++;
        ll cur=;
        for(int i=now;i>=;i--)
        {
        anser+=(((jie[n]*ni[i]%mod)*ni[n-i]%mod)*cuo[i])%mod;
        }
        cout<<anser%mod<<endl;
    }
    return ;
}

L:爆搜

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#define INF 2139062143
#define inf -2139062144
#define ll long long
using namespace std;
int qi[][];
bool flag;
int ini;
bool pan(int des) {
    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;
    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;
    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;

    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;
    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;
    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;

    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;
    if(qi[][] == qi[][] && qi[][] == qi[][] && qi[][] == des)    return true;
    return false;
}
bool dfs(int now,int step) {
    int i,j;
    if(step == ) {
        if(pan(ini))    flag = true;
        for(i=; i<; i++) {
            for(j=; j<; j++) {
//                printf("fuck:%d %d %d\n",i,j,qi[i][j]);
                if(qi[i][j] == ) {
                    qi[i][j] = ini;
                    if(pan(ini) == true)    flag = true;
                    if(dfs(now * (-),) == true)    flag = true;
                    qi[i][j] = ;
                }
            }
        }
    } else {
        if(step == ) {
            bool temp = true;
            for(i=; i<; i++) {
                for(j=; j<; j++) {
                    if(qi[i][j] == ) {
                        qi[i][j] = (ini*-);
                        if(pan(ini*-))    temp = false;
                        if(dfs(ini,) == false)    temp = false;
                        qi[i][j] = ;
                    }
                }
            }
            return temp;
        } else {
            if(step == ) {
                bool tt = false;
                for(i=; i<; i++) {
                    for(j=; j<; j++) {
                        if(qi[i][j] == ) {
                            qi[i][j] = ini;
                            if(pan(ini))    tt = true;
                            qi[i][j] = ;
                        }
                    }
                }
                return tt;
            }
        }
    }
}
int main() {
    int t;
    scanf("%d",&t);
    while(t--) {
        int i,j;
        getchar();
        for(i=; i<; i++) {
            for(j=; j<; j++) {
                char x[];
                scanf("%s",x);
                char te = x[];
                if(te == '.')    qi[i][j] = ;
                if(te == 'o')    qi[i][j] = ;
                if(te == 'x')    qi[i][j] = -;
            }
        }

        char x[];
        scanf("%s",x);
        char te = x[];
        int now;
        if(te == 'o')    now = ;
        if(te == 'x')    now = -;
        ini = now;
        flag = false;

        if(pan(ini * -) == true) {
            printf("Cannot win!\n");
        } else {
//            for(i=0; i<3; i++) {
//                for(j=0; j<3; j++)
//                    printf("%d ",qi[i][j]);
//                printf("\n");
//            }
            dfs(now,);
            if(flag)    printf("Kim win!\n");
            else    printf("Cannot win!\n");
        }
    }
    return ;
}