1. Ski race 枚举枚举倍数判断即可.时间复杂度$O(n\log m)$. #include<cstdio> #include<algorithm> using namespace std; int n,m,i,j,ans,flag,q[111111],a[111111]; bool v[11111111]; int main(){ freopen("input.txt","r",stdin); freopen("outpu…

A. Array Factory 将下标按前缀和排序,然后双指针,维护最大的右边界即可. #include<cstdio> #include<algorithm> using namespace std; typedef long long ll; const int N=200010; int n,i,j,anslen,ansl,ansr,mr,q[N]; ll a[N],lim; inline bool cmp(int x,int y){return a[x]<a[y];…

A. Artifact Guarding 选出的守卫需要满足$\max(a+b)\leq \sum a$,从小到大枚举每个值作为$\max(a+b)$,在权值线段树上找到最大的若干个$a$即可. 时间复杂度$O(n\log n)$. #include<cstdio> #include<algorithm> #include<set> #include<map> using namespace std; typedef long long ll; const…

A. Centroid Tree 枚举至多两个重心作为根,检查对于每个点是否都满足$2size[x]\leq size[father[x]]$即可. #include<stdio.h> #include<iostream> #include<string.h> #include<string> #include<ctype.h> #include<math.h> #include<set> #include<map&…

A. Arithmetic Derivative 形如$p^p(p是质数)$的数的比值为$1$,用$k$个这种数相乘得到的数的比值为$k$,爆搜即可. #include<cstdio> #include<algorithm> typedef unsigned long long ll; int K,cnt,all;ll n,i,q[100000],ans[1000000]; ll po(ll a,ll b){ ll t=1; while(b--){ if(t>n/a)retu…

A. Passage 枚举两个点,看看删掉之后剩下的图是否是二分图. #include <bits/stdc++.h> using namespace std ; const int MAXN = 205 ; vector < int > G[MAXN] ; int vis[MAXN] , col[MAXN] ; int n ; int dfs ( int u ) { for ( int i = 0 ; i < G[u].size () ; ++ i ) { int v =…

A. Apple 按题意模拟即可. #include<stdio.h> #include<iostream> #include<string.h> #include<string> #include<ctype.h> #include<math.h> #include<set> #include<map> #include<vector> #include<queue> #include…

A. Count The Ones $ans=b-c+1$. #include <stdio.h> using namespace std ; int a , b , c ; void solve () { printf ( "%d\n" , 1 + b - c ) ; } int main () { while ( ~scanf ( "%d%d%d" , &a , &b , &c ) ) solve () ; return 0…

A. Pieces of Parentheses 将括号串排序,先处理会使左括号数增加的串,这里面先处理减少的值少的串:再处理会使左括号数减少的串,这里面先处理差值较大的串.确定顺序之后就可以DP了. 时间复杂度$O(n^3)$. #include<cstdio> #include<cstring> #include<algorithm> using namespace std; const int N=310,inf=1000000; int n,i,j,m,all,…

题目:Problem A. Arithmetic DerivativeInput file: standard inputOutput file: standard inputTime limit: 1 secondMemory limit: 256 mebibytesLets define an arithmetic derivative:• if p = 1 then p0 = 0;• if p is prime then p0 = 1;• if p is not prime then n0…