Educational Codeforces Round 10

652A - Gabriel and Caterpillar 20171128

按题意模拟即可

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int h1,h2,a,b,ans=1;
int main()
{scanf("%d%d%d%d",&h1,&h2,&a,&b);if(h1+8*a>=h2)return printf("0\n"),0;if(a<=b)return printf("-1\n"),0;h1+=8*a-12*b;while(true){if(h1+12*a>=h2)return printf("%d\n",ans),0;h1+=12*(a-b),ans++;}
}

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652B - z-sort 20171128

排序之后把大的数字放偶数位即可

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int n,a[1001],ans[1001];
int main()
{scanf("%d",&n);int N=n;for(int i=1;i<=n;i++)scanf("%d",&a[i]);sort(a+1,a+n+1);for(int i=1;i<=n;i+=2)ans[i]=a[i+1>>1];for(int i=N-(N&1);i>=2;i-=2)ans[i]=a[n--];for(int i=1;i<=N;i++)printf("%d%c",ans[i],i==N?'\n':' ');return 0;
}

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652C - Foe Pairs 20171128

对每个数记录所有和他组成Foe Pair的数字位置即可

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#define N 300001
#include<vector> 
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define LL long long
#define MOD 1000000007
LL n,m,a,b,ans,p[N],pos[N];
vector<LL>f[N];
int main()
{scanf("%I64d%I64d",&n,&m);for(LL i=1;i<=n;i++)scanf("%I64d",&p[i]),pos[p[i]]=i;for(LL i=1;i<=m;i++){scanf("%I64d%I64d",&a,&b);if(pos[a]>pos[b])swap(a,b);f[pos[a]].push_back(pos[b]-1);}LL _=n;for(LL i=n;i>=1;i--){for(LL j=0;j<f[i].size();j++)_=min(_,f[i][j]);ans+=_-i+1;}printf("%I64d\n",ans);return 0;
}

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652D - Nested Segments 20190312

离散化后用树状数组处理即可

#include<bits/stdc++.h>
using namespace std;
#define N 200001
int n,l[N],r[N],a[N],f[N],t[N];
map<int,int>mp;
int lowbit(int x){return x&(-x);}
bool cmpl(int x,int y){return l[x]<l[y];}
bool cmpr(int x,int y){return r[x]<r[y];}
void change(int x,int c){while(x<N)t[x]+=c,x+=lowbit(x);}
int ask(int x){int res=0;while(x)res+=t[x],x-=lowbit(x);return res;}
int main()
{scanf("%d",&n);for(int i=1;i<=n;i++)scanf("%d%d",&l[i],&r[i]),a[i]=i;sort(a+1,a+n+1,cmpr);for(int i=1;i<=n;i++)mp[r[a[i]]]=i;sort(a+1,a+n+1,cmpl);for(int i=1;i<=n;i++)change(i,1);for(int i=1;i<=n;i++)change(mp[r[a[i]]],-1),f[a[i]]=ask(mp[r[a[i]]]);for(int i=1;i<=n;i++)printf("%d\n",f[i]);
}

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652E - Pursuit For Artifacts 20190402

缩点后深搜一次即可，注意细节处理

#include<bits/stdc++.h>
using namespace std;
#define N 300001
#define mp make_pair
stack<int>s,t;
vector<pair<int,int> >d[N],d2[N];
int n,m,u,v,z,cnt,dcnt,f[N],dfn[N],low[N],flg[N];
void dfs(int cur,int pre)
{s.push(cur);low[cur]=dfn[cur]=++dcnt;for(auto nxt:d[cur])if(nxt.first!=pre){if(!dfn[nxt.first])dfs(nxt.first,cur);low[cur]=min(low[cur],low[nxt.first]);}if(dfn[cur]==low[cur]){cnt++;while(s.top()!=cur)f[s.top()]=cnt,t.push(s.top()),s.pop();f[s.top()]=cnt,t.push(s.top()),s.pop();while(!t.empty()){int x=t.top();t.pop();for(auto y:d[x])if(f[x]==f[y.first])flg[cnt]|=y.second;}}
}
void dfs2(int cur,int pre)
{flg[cur]|=flg[pre];for(auto nxt:d2[cur])if(nxt.first!=pre)flg[nxt.first]|=nxt.second,dfs2(nxt.first,cur);
}
int main()
{scanf("%d%d",&n,&m);for(int i=1;i<=m;i++){scanf("%d%d%d",&u,&v,&z);d[u].push_back(mp(v,z));d[v].push_back(mp(u,z));}for(int i=1;i<=n;i++)sort(d[i].begin(),d[i].end());for(int i=1;i<=n;i++)if(!dfn[i])dfs(i,0);for(int i=1;i<=n;i++)for(auto j:d[i])if(f[i]!=f[j.first])d2[f[i]].push_back(mp(f[j.first],j.second));scanf("%d%d",&u,&v);dfs2(f[u],0);printf("%s\n",flg[f[v]]?"YES":"NO");return 0;
}