NOIP模拟10.24 R2

A

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 50010
#define inf 0x3f3f3f3f
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,d
,l=1,r;
inline bool jud(int x){
int last=0,res=0;
for(int i=1;i<=n;++i){
if(last+x<=d[i]) last=d[i];else res++;
}return res<=m;
}
int main(){
//  freopen("a.in","r",stdin);
r=read();n=read();m=read();
for(int i=1;i<=n;++i) d[i]=read();d[++n]=r;
while(l<=r){
int mid=l+r>>1;
if(jud(mid)) l=mid+1;else r=mid-1;
}printf("%d\n",l-1);
return 0;
}

B

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 1010
#define M 210
#define inf 0x3f3f3f3f
#define mod 1000000007
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,kk,dp[2][M][M],f[2][M][M],p=0;
//dp[i][j][k] a的前i个字符，匹配到b[j]，分为k段的方案数,f[i][j][k] 要求a[i]==b[j]的方案数
char a
,b[M];
int main(){
//  freopen("a.in","r",stdin);
n=read();m=read();kk=read();
scanf("%s%s",a+1,b+1);dp[0][0][0]=dp[1][0][0]=1;
for(int i=1;i<=n;++i){
for(int j=1;j<=m;++j)
for(int k=1;k<=kk;++k){
dp[p^1][j][k]=dp[p][j][k];f[p^1][j][k]=0;
if(a[i]!=b[j]) continue;
f[p^1][j][k]=(dp[p][j-1][k-1]+f[p][j-1][k])%mod;
dp[p^1][j][k]=(dp[p^1][j][k]+f[p^1][j][k])%mod;
}p^=1;
}printf("%d\n",dp[p][m][kk]);
return 0;
}

C

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 300010
#define inf 0x3f3f3f3f
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,h
,num=0,dep
,fa
[20],sum
[20],mx
[20],Log
,w
;
int len
,ans=0;
struct edge{
int to,next,val;
}data[N<<1];
vector<int>a
;
void dfs(int x){
for(int i=1;i<=Log
;++i){
if(!fa[x][i-1]) continue;
fa[x][i]=fa[fa[x][i-1]][i-1];
sum[x][i]=sum[x][i-1]+sum[fa[x][i-1]][i-1];
mx[x][i]=max(mx[x][i-1],mx[fa[x][i-1]][i-1]);
}
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x][0]) continue;
fa[y][0]=x;dep[y]=dep[x]+1;sum[y][0]=data[i].val;
mx[y][0]=data[i].val;w[y]=data[i].val;dfs(y);
}
}
void solve0(){
int x=read(),y=read(),mxx=0,summ=0;
if(dep[x]<dep[y]) swap(x,y);
int t=dep[x]-dep[y];
for(int i=Log[t];i>=0;--i)
if(t&(1<<i)) mxx=max(mxx,mx[x][i]),summ+=sum[x][i],x=fa[x][i];
if(x==y){printf("%d\n",summ-mxx);return;}
for(int i=Log
;i>=0;--i){
if(fa[x][i]==fa[y][i]) continue;
mxx=max(mxx,max(mx[x][i],mx[y][i]));summ+=sum[x][i]+sum[y][i];
x=fa[x][i],y=fa[y][i];
}mxx=max(mxx,max(mx[x][0],mx[y][0]));summ+=sum[x][0]+sum[y][0];
printf("%d\n",summ-mxx);return;
}
inline int lca(int x,int y){
if(dep[x]<dep[y]) swap(x,y);
int t=dep[x]-dep[y];
for(int i=Log[t];i>=0;--i)
if(t&(1<<i)) x=fa[x][i];
if(x==y) return x;
for(int i=Log
;i>=0;--i)
if(fa[x][i]!=fa[y][i]) x=fa[x][i],y=fa[y][i];
return fa[x][0];
}
int main(){
//  freopen("a.in","r",stdin);
n=read();m=read();Log[0]=-1;
for(int i=1;i<=n;++i) Log[i]=Log[i>>1]+1;
for(int i=1;i<n;++i){
int x=read(),y=read(),v=read();
data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=v;
data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=v;
}dfs(1);if(m==1){solve0();return 0;}
for(int i=1;i<=m;++i){
int x=read(),y=read(),t=lca(x,y);
while(x!=t) a[x].push_back(i),len[i]+=w[x],x=fa[x][0];
while(y!=t) a[y].push_back(i),len[i]+=w[y],y=fa[y][0];ans=max(ans,len[i]);
}for(int i=2;i<=n;++i){
int res=0;
for(int j=0;j<a[i].size();++j) len[a[i][j]]-=w[i];
for(int j=1;j<=m;++j) res=max(res,len[j]);ans=min(ans,res);
for(int j=0;j<a[i].size();++j) len[a[i][j]]+=w[i];
}printf("%d\n",ans);
return 0;
}

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
#define N 300010
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,m,h
,num=0,fa
[20],dep
,dis
,w
,Log
;
int mid,cnt,c
;
bool flag;
struct edge{
int to,next,val;
}data[N<<1];
struct Data{
int u,v,t,len;
}a
;
inline bool cmp(Data x,Data y){
return x.len>y.len;
}
void dfs(int x){
for(int i=1;i<=Log
;++i){
if(!fa[x][i-1]) continue;
fa[x][i]=fa[fa[x][i-1]][i-1];
}
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x][0]) continue;
fa[y][0]=x;dep[y]=dep[x]+1;w[y]=data[i].val;
dis[y]=dis[x]+w[y];dfs(y);
}
}
inline int lca(int x,int y){
if(dep[x]<dep[y]) swap(x,y);
int t=dep[x]-dep[y];
for(int i=Log[t];i>=0;--i)
if(t&(1<<i)) x=fa[x][i];
if(x==y) return x;
for(int i=Log
;i>=0;--i)
if(fa[x][i]!=fa[y][i]) x=fa[x][i],y=fa[y][i];
return fa[x][0];
}
int calc(int x){
int res=c[x];
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x][0]) continue;
res+=calc(y);if(flag) return res;
}if(res!=cnt) return res;
if(a[1].len-w[x]<=mid) flag=1;return res;
}
bool jud(){
cnt=0;memset(c,0,sizeof(c));flag=0;
for(int i=1;i<=m;++i){
if(a[i].len<=mid) break;cnt++;
c[a[i].u]++;c[a[i].v]++;c[a[i].t]-=2;
}calc(1);return flag;
}
int main(){
//  freopen("a.in","r",stdin);
n=read();m=read();Log[0]=-1;
for(int i=1;i<=n;++i) Log[i]=Log[i>>1]+1;
for(int i=1;i<n;++i){
int x=read(),y=read(),v=read();
data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=v;
data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=v;
}dfs(1);
for(int i=1;i<=m;++i){
a[i].u=read();a[i].v=read();a[i].t=lca(a[i].u,a[i].v);
a[i].len=dis[a[i].u]+dis[a[i].v]-2*dis[a[i].t];
}sort(a+1,a+m+1,cmp);
int l=0,r=a[1].len;
while(l<=r){
mid=l+r>>1;
if(jud()) r=mid-1;else l=mid+1;
}printf("%d\n",r+1);
return 0;
}