ACM常用模板——数据结构——区间最值查询RMQ

(一）基于ST的RMQ

#include<iostream>#include<cstdio>#include<cmath>using namespace std;const int maxn=100005;int dp[maxn][20],a[maxn],n,m;//s数组下标从0开始void init_rmq(){for(int i=0;i<n;i++) dp[i][0]=a[i];for(int j=1;(1<<j)<=n;j++)for(int i=0;i+(1<<j)-1<n;i++)    dp[i][j]=min(dp[i][j-1],dp[i+(1<<(j-1))][j-1]);}int rmq(int l,int r){    int k=(int)(log(1.0*(r-l+1))/log(2.0));    return min(dp[l][k],dp[r-(1<<k)+1][k]);}void init_rmq_index(){for(int i=0;i<n;i++) dp[i][0]=i;for(int j=1;(1<<j)<=n;j++)for(int i=0;i+(1<<j)-1<n;i++)        if(a[dp[i][j-1]]<a[dp[i+(1<<(j-1))][j-1]]) dp[i][j]=dp[i][j-1];    else dp[i][j]=dp[i+(1<<(j-1))][j-1];}int rmq_index(int l,int r){    int k=(int)(log(1.0*(r-l+1))/log(2.0));    if(a[dp[l][k]]<a[dp[r-(1<<k)+1][k]]) return dp[l][k];else return dp[r-(1<<k)+1][k];}int main(){ //  freopen("in.txt","r",stdin);  //  freopen("out.txt","w",stdout);    while(~scanf("%d",&n)){    for(int i=0;i<n;i++) scanf("%d",&a[i]);        init_rmq();        int l,r;        scanf("%d",&m);        for(int i=0;i<m;i++){            scanf("%d%d",&l,&r);            //printf("[%d,%d] = ",l,r);            printf("%d\n",rmq(l,r));}}return 0;}

（二）基于线段树的RMQ

#include<iostream>#include<cstdio>#include<cmath>#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1using namespace std;const int maxn=100005;int a[maxn],Min[maxn<<2],n;void PushUp(int rt){    Min[rt]=min(Min[rt<<1],Min[rt<<1|1]);}void build(int l,int r,int rt){    if(l==r){        Min[rt]=a[l];        return ;}    int m=(l+r)>>1;    build(lson);    build(rson);    PushUp(rt);}int Query(int L,int R,int l,int r,int rt){    if(L<=l&&r<=R) return Min[rt];    int m=(l+r)>>1,ans=1<<30;    if(L<=m) ans=min(ans,Query(L,R,lson));    if(R>m) ans=min(ans,Query(L,R,rson));    return ans;}int main(){   // freopen("in.txt","r",stdin);    while(~scanf("%d",&n)){        for(int i=1;i<=n;i++) scanf("%d",&a[i]);        build(1,n,1);        int l,r,m;         scanf("%d",&m);        for(int i=0;i<m;i++){            scanf("%d%d",&l,&r);            //printf("[%d,%d] = ",l,r);            printf("%d\n",Query(l+1,r+1,1,n,1));}}return 0;}

#define LL long long

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1 | 1

using namespace std;

const int maxn=400005,maxe=100005,inf=1<<29;

int n,m,k;

int Rank[maxn],tmp[maxn],sa[maxn],height[maxn];

char s[maxn],s1[maxn];

int dp[maxn][30];

bool cmp(int i,int j)

{

if(Rank[i]!=Rank[j]) return Rank[i]<Rank[j];

else

{

int ri=i+k<=n?Rank[i+k]:-1;

int rj=j+k<=n?Rank[j+k]:-1;

return ri<rj;

}

}

void get_sa()

{

for(int i=0;i<=n;i++)

{

sa[i]=i;

Rank[i]=(i<n?s[i]:-1);

}

for(k=1;k<=n;k*=2)

{

sort(sa,sa+n+1,cmp);

tmp[sa[0]]=0;

for(int i=1;i<=n;i++) tmp[sa[i]]=tmp[sa[i-1]]+(cmp(sa[i-1],sa[i])?1:0);

    for(int i=0;i<=n;i++) Rank[i]=tmp[i];

}

}

void get_lcp()

{

for(int i=0;i<=n;i++) Rank[sa[i]]=i;

int h=0;height[0]=0;

for(int i=0;i<n;i++)

{

int j=sa[Rank[i]-1];

if(h>0) h--;

for(;j+h<n&&i+h<n;h++)

if(s[j+h]!=s[i+h]) break;

height[Rank[i]-1]=h;

}

}

void InitRMQ()

{

for(int i=0;i<n;i++) dp[i][0]=height[i];

for(int j=1;(1<<j)<=n;j++)

for(int i=0;i+(1<<j)-1<n;i++)

dp[i][j]=min(dp[i][j-1],dp[i+(1<<(j-1))][j-1]);

}

int RMQ(int l,int r)

{

int mi=(int)(log((r-l+1)*1.0)/log(2.0));

return min(dp[l][mi],dp[r-(1<<mi)+1][mi]);

}

int main()

{

while(~scanf("%s",s1))

{

int  n1=strlen(s1);

memcpy(s,s1,sizeof(s1));

s[strlen(s)]='$';

reverse(s1,s1+strlen(s1));

memcpy(s+strlen(s1)+1,s1,sizeof(s1));

n=strlen(s);

get_sa();

get_lcp();

n++;

InitRMQ();

int ans=0;

for(int i=0;i<n1;i++)

{

int j=2*n1-i;

int v=RMQ(min(Rank[i],Rank[j]),max(Rank[i],Rank[j])-1);

ans=max(ans,2*v-1);

  }

for(int i=1;i<n1;i++)

  {

int j=2*n1-i+1;

int v=RMQ(min(Rank[i],Rank[j]),max(Rank[i],Rank[j])-1);

ans=max(ans,2*v);

  }

printf("%d\n",ans);

}

return 0;

}

//abracadabra

#include<cstdio>

#include<iostream>

using namespace std;

const int maxn=400005;

char s[maxn],str[maxn];

int p[maxn];

void init()

{

int i,l;

s[0]='@';s[1]='#';

for(i=0,l=2;str[i];i++,l+=2) s[l]=str[i],s[l+1]='#';

s[l]=0;

}

int Manacher()

{

int ans=0,mx=0,id;

for(int i=0;s[i];i++)

{

if(mx>i) p[i]=min(p[2*id-i],mx-i);

    else p[i]=1;

while(s[i+p[i]]==s[i-p[i]]) p[i]++;

if(i+p[i]>mx) mx=i+p[i],id=i;

ans=max(ans,p[i]);

}

return ans-1;

}

int main()

{

while(~scanf("%s",str))

{

init();

printf("%d\n",Manacher());

}

return 0;

}