2017年8月17日（模拟8smoj2066，2067，2068质因子求组合，线段树求逆序对，深度搜索

#include <stdio.h>using namespace std;#define ll long long#define maxN 50010#define F(i,j,n)for (int i=j; i<=n; i++)int n,m,P;ll check[maxN];ll p[maxN],a[maxN],b[maxN],k[maxN];int tot;void prime(int n){tot=0;F(i,2,n){if (!check[i])p[++tot]=i;F(j,1,tot){if (i*p[j]>=maxN)break;check[i*p[j]]=1;if (i%p[j]==0)break;}}}ll ask(ll x,ll z){ll sum=1,x1=x;for (int i=0; (1<<i)<=z; i++){if (z&(1<<i))sum=(sum*x1)%P;x1*=x1;}return sum;} int main(){freopen("2066.in","r",stdin);freopen("2066.out","w",stdout);scanf("%d%d%d",&n,&m,&P);if (m>n-m)m=n-m;F(i,0,m-1)a[i]=n-i;F(i,1,m)b[i]=i;prime(n);F(i,0,m-1)F(j,1,tot){while (a[i]%p[j]==0)a[i]/=p[j],k[j]++;if (a[i]==1)break;}F(i,2,m)F(j,1,tot){while (b[i]%p[j]==0)b[i]/=p[j],k[j]--;if (b[i]==1)break;}ll ans=1;F(i,1,tot)ans=(ans*ask(p[i],k[i]))%P; printf("%lld\n",ans); return 0;}

#include <stdio.h>#include <algorithm>#include <cstring>using namespace std;#define maxN 200010#define ll long long#define F(i,j,n)for (int i=j; i<=n; i++)int n;ll tr[maxN*4],a[maxN*2],f[maxN];void update(int l,int r,int root,int pos){if (l==r){tr[root]++;return ;}int mid=(l+r)/2;if (l<=pos && pos<=mid)update(l,mid,root*2,pos);if (mid<pos && pos<=r)update(mid+1,r,root*2+1,pos);tr[root]=tr[root*2]+tr[root*2+1];}ll query(int L,int R,int root,int l,int r){if (l>R || L>r)return 0;if (l<=L && R<=r)return tr[root];return query(L,(L+R)/2,root*2,l,r)+query((L+R)/2+1,R,root*2+1,l,r);}int main(){freopen("2067.in","r",stdin);freopen("2067.out","w",stdout);scanf("%d",&n);ll ans=0;memset(tr,0,sizeof tr);memset(f,0,sizeof f);int cnt=0;F(i,1,n*2){scanf("%d",&a[i]);if (!f[a[i]])f[a[i]]=++cnt;}F(i,1,n*2){a[i]=f[a[i]];update(1,n,1,a[i]);ans+=query(1,n,1,a[i]+1,n);}printf("%lld",ans);return 0;}

#include <stdio.h>#include <cstring>#include <algorithm>using namespace std;#define maxN 200010#define F(i,j,n)for (int i=j; i<=n; i++)struct Tnode{int v,w,nxt;}edge[maxN];struct Tpoint{int w,bh;}p[maxN][4];int first[maxN],tot;int du[maxN],used[maxN];int n;void init() {memset(first,-1,sizeof first);tot=0;}void add(int u,int v,int w){edge[++tot].v=v,edge[tot].w=w,edge[tot].nxt=first[u],first[u]=tot;}void insert(int v,int max_v,int u){if (max_v>p[u][0].w){p[u][3]=p[u][2],p[u][2]=p[u][1],p[u][1]=p[u][0];p[u][0].bh=v,p[u][0].w=max_v;}elseif (max_v>p[u][1].w){p[u][3]=p[u][2],p[u][2]=p[u][1];p[u][1].bh=v,p[u][1].w=max_v;}elseif (max_v>p[u][2].w){p[u][3]=p[u][2];p[u][2].bh=v,p[u][2].w=max_v;}elseif (max_v>p[u][3].w){p[u][3].bh=v,p[u][3].w=max_v;}}void dfs(int u){used[u]=1;for (int i=first[u]; i!=-1; i=edge[i].nxt){int v=edge[i].v;if (!used[v]){dfs(v);int max_v=p[v][0].w+edge[i].w;insert(v,max_v,u);}}}void ask(int u){used[u]=1;for (int i=first[u]; i!=-1; i=edge[i].nxt){int v=edge[i].v;if (!used[v]){F(j,0,3)if (p[u][j].bh!=v){int max_u=p[u][j].w+edge[i].w;insert(u,max_u,v);break;}ask(v);}}}int main(){freopen("2068.in","r",stdin);freopen("2068.out","w",stdout);scanf("%d",&n);init();F(i,1,n-1){int u,v,w;scanf("%d%d%d",&u,&v,&w);du[u]++,du[v]++;add(u,v,w);add(v,u,w);}dfs(1);memset(used,0,sizeof used);ask(1);int ans=-1;F(i,1,n)if (du[i]>=4)ans=max(ans,p[i][0].w+p[i][1].w+p[i][2].w+p[i][3].w);printf("%d\n",ans);return 0;}