不可重叠最长重复子串

  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;
 78 bool check(int k){
 79     int maxsa=sa[0],minsa=sa[0];
 80     for (int i=1;i<n;i++){
 81         if (height[i]>=k){
 82             minsa = min(sa[i],minsa);
 83             maxsa = max(sa[i],maxsa);
 84         }
 85         else{
 86             if (maxsa-minsa>=k)
 87                 return true;
 88             maxsa = sa[i];
 89             minsa = sa[i];
 90         }
 91     }
 92     if (maxsa-minsa>=k){
 93         return true;
 94     }
 95     return false;
 96 }
 97 
 98 int main(){
 99     while (~scanf("%d",&n) && n!=0){
100         for (int i=0;i<n;i++){
101             scanf("%d",&s[i]);
102         }
103         for (int i=0;i<n;i++){
104             if (i == n-1)
105                 s[i] = 0;
106             else
107                 s[i] = s[i+1]-s[i] + 100;
108         }
109         build_sa(n,200);
110         getHeight(n-1);
111         int l=0,r=n,mid;
112         while (l<=r){
113             mid = (l+r)>>1;
114             if (check(mid)){
115                 l = mid+1;
116             }
117             else{
118                 r = mid-1;
119             }
120         }
121         if (r<4){
122             printf("0\n");
123         }
124         else{
125             printf("%d\n",r+1);
126         }
127     }
128     return 0;
129 }