选数
排序原数列，二分答案，对于差值<mid的相邻对进行删除
#include<map>
#include<stack>
#include<queue>
#include<cstdio>
#include<string>
#include<vector>
#include<cstring>
#include<complex>
#include<iostream>
#include<assert.h>
#include<algorithm>
using namespace std;
#define inf 1001001001
#define infll 1001001001001001001LL
#define ll long long
#define dbg(vari) cerr<<#vari<<" = "<<(vari)<<endl
#define gmax(a,b) (a)=max((a),(b))
#define gmin(a,b) (a)=min((a),(b))
#define Ri register int
#define gc getchar()
#define il inline
il int read(){
bool f=true;Ri x=0;char ch;while(!isdigit(ch=gc))if(ch==‘-‘)f=false;while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-‘0‘;ch=gc;}return f?x:-x;
}
#define gi read()
#define FO(x) freopen(#x".in","r",stdin),freopen(#x".out","w",stdout);
int n,k,a[100002],p[100002],g[100002];
bool chk(int x){
int cnt=0,_p=a[1],mn;
for(int i=2;i<=n;i++){
if(a[i]-_p<x)++cnt;
else _p=a[i];
}
return n-cnt>=k;
}
int main(){
FO(choose);
n=gi;k=gi;
for(int i=1;i<=n;i++)a[i]=gi;
sort(a+1,a+n+1);
for(int i=2;i<=n;i++)g[i]=a[i]-a[i-1];
int l=1,r=1000000001,ans;
while(l<=r){
int mid=(l+r)/2;
if(chk(mid)){
ans=mid;
l=mid+1;
}
else r=mid-1;
}
cout<<ans;
}
划区灌溉
易得f[i]=min{f[j]}+1 (
)
然后用个单调队列
#include<stack>
#include<queue>
#include<cstdio>
#include<string>
#include<vector>
#include<cstring>
#include<complex>
#include<iostream>
#include<assert.h>
#include<algorithm>
using namespace std;
#define inf 1001001001
#define infll 1001001001001001001LL
#define ll long long
#define dbg(vari) cerr<<#vari<<" = "<<(vari)<<endl
#define gmax(a,b) (a)=max((a),(b))
#define gmin(a,b) (a)=min((a),(b))
#define Ri register int
#define gc getchar()
#define il inline
il int read(){
bool f=true;Ri x=0;char ch;while(!isdigit(ch=gc))if(ch==‘-‘)f=false;while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-‘0‘;ch=gc;}return f?x:-x;
}
#define gi read()
#define FO(x) freopen(#x".in","r",stdin),freopen(#x".out","w",stdout);
const int maxn=1000033;
int dq[1234567],f[1234567],map[1234567];
int n,m,L,A,B;
int main(){
FO(divide);
n=gi;L=gi;A=gi;B=gi;
memset(f,127/2,sizeof(f));
int a,b;
for(int i=1;i<=n;i++)
a=gi,b=gi,map[min(a+1,b)]++,map[b]--;
a=(A-B)<<1,b=0;int H=1,T=0;
f[0]=0;
int now=0;
for(int i=1;i<A*2;i++) now+=map[i];
for(int i=A<<1;i<=L;i+=2,a+=2,b+=2){
while(H<=T&&f[dq[T]]>=f[b]) T--;
dq[++T]=b;
if(f[dq[T]]>=inf) T--;
now+=map[i]+map[i-1];
if(now){
f[i]=inf;
continue;
}
while(H<=T&&dq[H]<a) H++;
if(H<=T&&f[dq[H]]<inf)f[i]=f[dq[H]]+1;
else f[i]=inf;
}
printf("%d\n",f[L]<inf?f[L]:-1);
return 0;
}
树林
从树林连一条线到边界。然后根据在边界两侧的情况bfs
#include<map>
#include<stack>
#include<queue>
#include<cstdio>
#include<string>
#include<vector>
#include<cstring>
#include<complex>
#include<iostream>
#include<assert.h>
#include<algorithm>
using namespace std;
#define inf 1001001001
#define infll 1001001001001001001LL
#define ll long long
#define dbg(vari) cerr<<#vari<<" = "<<(vari)<<endl
#define gmax(a,b) (a)=max((a),(b))
#define gmin(a,b) (a)=min((a),(b))
#define Ri register int
#define gc getchar()
#define il inline
il int read(){
bool f=true;Ri x=0;char ch;while(!isdigit(ch=gc))if(ch==‘-‘)f=false;while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-‘0‘;ch=gc;}return f?x:-x;
}
#define gi read()
#define FO(x) freopen(#x".in","r",stdin),freopen(#x".out","w",stdout);
int n,m,sx,sy,x,y;
struct data{
int x,y,f;
};
int dx[]={0,0,1,1,1,-1,-1,-1};
int dy[]={1,-1,-1,0,1,1,-1,0};
int a[55][55],b[55][55],flag[2][55][55];
int main(){
FO(grove);
n=gi;m=gi;
for(int i=1;i<=n;i++)
for(int j=1;j<=m;j++){
char ch=gc;
while(ch!=‘.‘&&ch!=‘X‘&&ch!=‘*‘)ch=gc;
if(ch==‘X‘)a[i][j]=1,x=i,y=j;
if(ch==‘*‘)sx=i,sy=j;
}
queue<data>q;
q.push((data){sx,sy,0});
for(int i=1;i<=n-x;i++)b[i+x][y]=1;
while(!q.empty()){
data c=q.front();q.pop();
for(int i=0;i<8;i++){
int X=c.x+dx[i],Y=c.y+dy[i];
if(X<=n&&X>0&&Y<=m&&Y>0&&!a[X][Y]){
if((b[c.x][c.y]||b[X][Y])&&Y<=c.y)continue;
if(b[X][Y]&&!flag[1][X][Y]){
flag[1][X][Y]=flag[c.f][c.x][c.y]+1;
q.push((data){X,Y,1});
}else{
if(!flag[c.f][X][Y]){
flag[c.f][X][Y]=flag[c.f][c.x][c.y]+1;
q.push((data){X,Y,c.f});
}
}
}
}
}
cout<<flag[1][sx][sy];
}
迷宫花坛
仙人掌最短路。
把环缩了。然后根据两点的位置分类讨论
#include<map>
#include<stack>
#include<queue>
#include<cstdio>
#include<string>
#include<vector>
#include<cstring>
#include<complex>
#include<iostream>
#include<assert.h>
#include<algorithm>
using namespace std;
#define inf 1001001001
#define infll 1001001001001001001LL
#define ll long long
#define dbg(vari) cerr<<#vari<<" = "<<(vari)<<endl
#define gmax(a,b) (a)=max((a),(b))
#define gmin(a,b) (a)=min((a),(b))
#define Ri register int
#define gc getchar()
#define il inline
il int read(){
bool f=true;Ri x=0;char ch;while(!isdigit(ch=gc))if(ch==‘-‘)f=false;while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-‘0‘;ch=gc;}return f?x:-x;
}
#define gi read()
#define FO(x) freopen(#x".in","r",stdin),freopen(#x".out","w",stdout);
const int N=100010,M=300010;
using namespace std;
int n,m,Q,dis[N],sta[N],top;
int rdis[N],rcnt,fa[N][22],dfn[N],pre[N],bel[N],rlen[N],dep[N];
struct edge{
int to,next,val;
}e[M*2];
int last[N],cnt=1,tim;
bool inq[N],del[M],vis[N];
void add(int a,int b,int c){
e[++cnt]=(edge){b,last[a],c};last[a]=cnt;
}
void ins(int a,int b,int c){add(a,b,c),add(b,a,c);}
void spfa(){
queue<int>q;
for(int i=1;i<=N;i++)dis[i]=inf;
dis[1]=0;q.push(1);inq[1]=1;
while(!q.empty()){
int x=q.front();q.pop();
for(int y=last[x];y;y=e[y].next){
if (dis[e[y].to]>dis[x]+e[y].val){
dis[e[y].to]=dis[x]+e[y].val;
if (!inq[e[y].to]){
q.push(e[y].to);
inq[e[y].to]=1;
}
}
}
inq[x]=0;
}
}
void getring(int st,int ed,int id){
del[id]=del[id^1]=1;
rlen[++rcnt]+=e[id].val;
for(int x=ed;x!=st;x=e[pre[x]^1].to){
bel[x]=rcnt;
del[pre[x]]=del[pre[x]^1]=1;
ins(st,x,0);
rlen[rcnt]+=e[pre[x]].val;
}
}
void dfs(int x){
dfn[x]=++tim;
for (int y=last[x];y;y=e[y].next)
if(y!=(pre[x]^1)&&(y<=(m*2+1))){
if(!dfn[e[y].to])
pre[e[y].to]=y,rdis[e[y].to]=rdis[x]+e[y].val,dfs(e[y].to);
else if(dfn[e[y].to]<dfn[x])
getring(e[y].to,x,y);
}
}
void dfs2(int x){
vis[x]=1;
for(int i=1;i<=17;i++) fa[x][i]=fa[fa[x][i-1]][i-1];
for(int y=last[x];y;y=e[y].next)
if(!del[y]&&e[y].to!=fa[x][0])
dep[e[y].to]=dep[x]+1,fa[e[y].to][0]=x,dfs2(e[y].to);
}
int query(int x,int y){
if(dep[x]<dep[y]) swap(x,y);
int a=x,b=y;
for(int h=dep[x]-dep[y],i=17;h&&i>=0;i--) if(h&(1<<i))h-=(1<<i),x=fa[x][i];
if(x==y) return dis[a]-dis[b];
for(int i=17;i>=0;i--)
if(fa[x][i]!=fa[y][i])
x=fa[x][i],y=fa[y][i];
int lca=fa[x][0];
if(bel[x]&&bel[x]==bel[y]){
int d=abs(rdis[x]-rdis[y]);d=min(d,rlen[bel[x]]-d);
return dis[a]+dis[b]-dis[x]-dis[y]+d;
}
return dis[a]+dis[b]-2*dis[lca];
}
int main(){
FO(garden);
n=gi;m=gi;
for(int i=1,x,y,z;i<=m;i++) x=gi,y=gi,z=gi,ins(x,y,z);
spfa();
pre[1]=-1;
dfs(1);dfs2(1);
Q=gi;
for(int i=1;i<=Q;i++) printf("%d\n",query(gi,gi));
return 0;
}
时间： 2024-11-05 11:49:30