140. Suffix Array (hash + bisection / suffix array)

Topic links: https://www.acwing.com/problem/content/description/142/

Hash + bisection

 

#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5 + 7;

typedef unsigned long long ull;
const ull mod = 131;

ull p[maxn],h[maxn];
int sa[maxn],rank[maxn],height[maxn];
char str[maxn];
int n ;
ull get(int x,int y){
    return h[y] - h[x - 1] * p[y - x + 1];
}

int lcp(int x,int y){
    int l = 0 ,r = min(n - x + 1,n - y + 1);
    while(l < r){
        int mid = (l + r + 1) >> 1;
        if(get(x,x + mid - 1) != get(y,y + mid - 1)) r = mid - 1;
        else l = mid;
    }
    return l;
}

bool cmp(int x , int y){
    int l = lcp(x,y);
    int av = x + l > n ? INT_MIN : str[x + l];
    int bv = y + l > n ? INT_MIN : str[y + l];
    return str[x + l] < str[y + l];
}

int main(){
    scanf("%s",str + 1);
    n = strlen(str + 1);
    p[0] = 1;
    for(int i = 1;i <= n ;i ++){
        p[i] = mod * p[i-1];
        h[i] = mod * h[i-1] + str[i] - '0' + 1;
        sa[i] = i;
    }
    sort(sa + 1, sa + 1 + n , cmp);
    for(int i = 2;i <= n ;i ++){
        height[i] = lcp(sa[i],sa[i-1]);
    }
    for(int i = 1;i <= n ;i ++) printf("%d%c",sa[i]-1," \n"[i==n]);
    printf("0 ");
    for(int i = 2;i <= n ;i ++) printf("%d%c",height[i]," \n"[i==n]);
    return 0;
}

Suffix array

#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5 + 7;

struct DA{
    bool cmp(int *r,int a,int b,int l){
        return r[a]==r[b]&&r[a+l]==r[b+l];
    }
    int t1[maxn],t2[maxn],c[maxn];
    int rank[maxn],height[maxn],RMQ[maxn],mm[maxn];
    int best[20][maxn];
    int r[maxn];
    int sa[maxn];
    int str[maxn];
    void da(int n,int m){
        n++;
        int i,j,p,*x=t1,*y=t2;
        for(i=0;i<m;i++)c[i]=0;
        for(i=0;i<n;i++)c[x[i]=str[i]]++;
        for(i=1;i<m;i++)c[i]+=c[i-1];
        for(i=n-1;i>=0;i--)sa[--c[x[i]]]=i;
        for(j=1;j<=n;j<<=1){
            p=0;
            for(i=n-j;i<n;i++)y[p++]=i;
            for(i=0;i<n;i++)if(sa[i]>=j)y[p++]=sa[i]-j;
            for(i=0;i<m;i++)c[i]=0;
            for(i=0;i<n;i++)c[x[y[i]]]++;
            for(i=1;i<m;i++)c[i]+=c[i-1];
            for(i=n-1;i>=0;i--)sa[--c[x[y[i]]]]=y[i];
            swap(x,y);
            p=1;x[sa[0]]=0;
            for(i=1;i<n;i++)
                x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;
            if(p>=n)break;
            m=p;
        }
        int k=0;
        n--;
        for(i=0;i<=n;i++)rank[sa[i]]=i;
        for(i=0;i<n;i++){
            if(k)k--;
            j=sa[rank[i]-1];
            while(str[i+k]==str[j+k])k++;
            height[rank[i]]=k;
        }
    }
    void initRMQ(int n){
        for(int i=1;i<=n;i++)RMQ[i]=height[i];
        mm[0]=-1;
        for(int i=1;i<=n;i++)
            mm[i]=((i&(i-1))==0)?mm[i-1]+1:mm[i-1];
        for(int i=1;i<=n;i++)best[0][i]=i;
        for(int i=1;i<=mm[n];i++)
        for(int j=1;j+(1<<i)-1<=n;j++){
            int a=best[i-1][j];
            int b=best[i-1][j+(1<<(i-1))];
            if(RMQ[a]<RMQ[b])best[i][j]=a;
            else best[i][j]=b;
        }
    }
    int askRMQ(int a,int b){
        int t;
        t=mm[b-a+1];
        b-=(1<<t)-1;
        a=best[t][a];b=best[t][b];
        return RMQ[a]<RMQ[b]?a:b;
    }
    int lcp(int a,int b){
        a=rank[a];b=rank[b];
        if(a>b)swap(a,b);
        return height[askRMQ(a+1,b)];
    }
    void print(int n){
       // cout<<"sa[] ";
        for(int i=2;i<=n;i++)cout<<sa[i]<<" ";cout<<endl;
        // cout<<"rank[] ";
        // for(int i=2;i<=n;i++)cout<<rank[i]<<" ";cout<<endl;
        //cout<<"height[] ";
        for(int i=2;i<=n;i++)cout<<height[i]<<" ";cout<<endl;
    }
}AA,BB;
//n=8;
//* Num [] = {1, 1, 2, 1, 1, 1, 1, 2, $}; num Note that the last one is 0, the other is greater than 0
 // * Rank [] =. 4,. 6,. 8,. 1 , 2, 3, 5, 7 , 0; rank [0 n-1] is a valid value, rank [n] is necessarily invalid value 0
 // * SA [] =. 8,. 3,. 4,. 5, 0,. 6, 1, 7, 2; sa [ 1 n] is a significant value, sa [0] is necessarily n is an invalid value 
 // * height [] = 0, 0,. 3, 2,. 3,. 1, 2, 0,. 1; height [2 n] is a valid value 

int main ( int argc, char  const * the argv []) 
{ 
    String STR; 
    CIN >> STR;
     for ( int I = 0 ; I <str.size (); I ++) AA .str [I] = STR [I] - ' 0 ' + 100 ; 
    AA.str [str.size ()]= 0;
    AA.da(str.size() + 1,600);
    AA.print(str.size() + 1);
    return 0;
}