Some will be found to fill the center of a character string of the longest palindrome, then binary hash + / manacher i is determined in the center of the maximum length (i.e., will fill all possible palindromic sequence, a total of n) , these greedy palindromic sequence selected farthest end position before the current position according to the left Permutation
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define N 100005 4 #define mod 1000000007 5 pair<int,int>hw[N]; 6 int n,ma,ans,s1[N],s2[N],mi[N]; 7 char s[N],ss[N]; 8 int hash1(int x,int y){ 9 return (s1[y]-1LL*s1[x]*mi[y-x]%mod+mod)%mod; 10 } 11 int hash2(int x,int y){ 12 return (s2[y]-1LL*s2[x]*mi[x-y]%mod+mod)%mod; 13 } 14 int main(){ 15 while (scanf("%s",ss)!=EOF){ 16 n=0; 17 for(int i=0;ss[i];i++){ 18 s[++n]='{'; 19 s[++n]=ss[i]; 20 } 21 s[++n]='{'; 22 s2[n+1]=0; 23 mi[0]=1; 24 for(int i=1;i<=n;i++)mi[i]=mi[i-1]*29LL%mod; 25 for(int i=1;i<=n;i++)s1[i]=(s1[i-1]*29LL+s[i]-'a')%mod; 26 for(int i=n;i;i--)s2[i]=(s2[i+1]*29LL+s[i]-'a')%mod; 27 for(int i=1;i<=n;i++){ 28 int l=0,r=min(i,n-i); 29 while (l<r){ 30 int mid=(l+r+1>>1); 31 if (hash1(i,i+mid)==hash2(i,i-mid))l=mid; 32 else r=mid-1; 33 } 34 hw[i]=make_pair(i-l,i+l); 35 } 36 sort(hw+1,hw+n+1); 37 ma=ans=0; 38 for(int i=1,j=1;i<=n;i++){ 39 if (hw[i].first>j){ 40 j=ma; 41 ma=0; 42 ans++; 43 } 44 if (hw[i].second>j)ma=max(ma,hw[i].second); 45 } 46 printf("%d\n",ans-1); 47 } 48 }