可重叠k次最长重复子串

  1 #include <stdio.h>
  2 #include <iostream>
  3 #include <algorithm>
  4 #include <string.h>
  5 #include <stdlib.h>
  6 #include <math.h>
  7 #include <queue>
  8 #include <set>
  9 
 10 #define INF 0x3f3f3f3f
 11 #define pii pair<int,int>
 12 #define LL long long
 13 using namespace std;
 14 typedef unsigned long long ull;
 15 const int maxn = 2e6+6;
 16 
 17 int s[maxn];
 18 int sa[maxn],t[maxn],t2[maxn],c[maxn];
 19 int Rank[maxn],height[maxn];
 20 
 21 void build_sa(int n,int m)
 22 {
 23     int i,j,*x=t,*y=t2;
 24     for (i=0;i<m;i++)
 25         c[i] = 0;
 26     for (i=0;i<n;i++)
 27         c[x[i] = s[i]]++;
 28     for (i=1;i<m;i++)
 29         c[i] += c[i-1];
 30     for (i=n-1;i>=0;i--)
 31         sa[--c[x[i]]] = i;
 32     for (int k=1;k<=n;k<<=1)
 33     {
 34         int p = 0;
 35         for (i=n-k;i<n;i++)
 36             y[p++] = i;
 37         for (i=0;i<n;i++)
 38         {
 39             if (sa[i]>=k)
 40                 y[p++] = sa[i]-k;
 41         }
 42         for (i=0;i<m;i++)
 43             c[i] = 0;
 44         for (i=0;i<n;i++)
 45             c[x[y[i]]]++;
 46         for (i=1;i<m;i++)
 47             c[i] += c[i-1];
 48         for (i=n-1;i>=0;i--)
 49             sa[--c[x[y[i]]]] = y[i];
 50         swap(x,y);
 51         p = 1;
 52         x[sa[0]] = 0;
 53         for (i=1;i<n;i++)
 54             x[sa[i]] = y[sa[i-1]] == y[sa[i]] && y[sa[i-1]+k]==y[sa[i]+k]?p-1:p++;
 55         if (p>=n)
 56             break;
 57         m = p;
 58     }
 59 }
 60 
 61 
 62 void getHeight(int n){
 63     int i,j,k=0;
 64     for (i=1;i<=n;i++){
 65         Rank[sa[i]] = i;
 66     }
 67     for (i=0;i<n;i++){
 68         if (k)
 69             k--;
 70         j = sa[Rank[i]-1];
 71         while (s[i+k] == s[j+k])
 72             k++;
 73         height[Rank[i]] = k;
 74     }
 75 }
 76 
 77 int n,k;
 78 int b[maxn];
 79 
 80 void Discretization(){
 81     for (int i=0;i<=n;i++){
 82         b[i] = s[i];
 83     }
 84     sort(b,b+n+1);
 85     int size = unique(b,b+n+1)-b;
 86     for (int i=0;i<=n;i++){
 87         s[i] = lower_bound(b,b+size,s[i])-b;
 88     }
 89 }
 90 
 91 bool check(int x){
 92     int tot = 1;
 93     for (int i=1;i<=n;i++){
 94         if (height[i]>=x)
 95             tot++;
 96         else{
 97             if (tot>=k)
 98                 return true;
 99             tot = 1;
100         }
101     }
102     return tot>=k;
103 }
104 
105 int main(){
106     while (~scanf("%d%d",&n,&k)){
107         for (int i=0;i<n;i++){
108             scanf("%d",&s[i]);
109         }
110         s[n] = 0;
111         Discretization();
112         build_sa(n+1,n+1);
113         getHeight(n);
114         int l=0,r=n,mid;
115         while (l<=r){
116             mid = (l+r)>>1;
117             if (check(mid)){
118                 l = mid+1;
119             }
120             else{
121                 r = mid-1;
122             }
123         }
124         printf("%d\n",r);
125     }
126     return 0;
127 }