Palindromic characteristics of string s with length |s| is a sequence of |s| integers, where k-th number is the total number of non-empty substrings of s which are k-palindromes.
A string is 1-palindrome if and only if it reads the same backward as forward.
A string is k-palindrome (k > 1) if and only if:
- Its left half equals to its right half.
- Its left and right halfs are non-empty (k - 1)-palindromes.
The left half of string t is its prefix of length ⌊|t| / 2⌋, and right half — the suffix of the same length. ⌊|t| / 2⌋ denotes the length of string tdivided by 2, rounded down.
Note that each substring is counted as many times as it appears in the string. For example, in the string "aaa" the substring "a" appears 3 times.
The first line contains the string s (1 ≤ |s| ≤ 5000) consisting of lowercase English letters.
Print |s| integers — palindromic characteristics of string s.
abba
6 1 0 0
abacaba
12 4 1 0 0 0 0
In the first example 1-palindromes are substring «a», «b», «b», «a», «bb», «abba», the substring «bb» is 2-palindrome. There are no 3- and 4-palindromes here.
#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <vector>
#include <bitset>
using namespace std;
#define LL long long
const int INF = 0x3f3f3f3f;
#define mod 10000007
#define mem(a,b) memset(a,b,sizeof a)
int dp[5005][5005];
char s[5005];
int ans[50005];
int main()
{
while(~scanf("%s",s))
{
int n=strlen(s);
mem(dp,0);
mem(ans,0);
for(int i=0; i<n; i++)
{
ans[1]++;
dp[i][i]=1;
}
for(int i=1; i<n; i++)
{
if(s[i-1]==s[i])
dp[i-1][i]=2,ans[1]++,ans[2]++;
}
for(int j=2; j<n; j++)
for(int i=0; i<n; i++)
{
if(i+j>=n)
break;
if(s[i]==s[i+j]&&dp[i+1][i+j-1])
{
dp[i][i+j]=dp[i][i+(j+1)/2-1]+1;
for(int q=1; q<=dp[i][i+j]; q++)
{
ans[q]++;
}
}
}
for(int i=1; i<n; i++)
printf("%d ",ans[i]);
printf("%d\n",ans[n]);
}
return 0;
}

本文介绍了一种算法,用于解决给定字符串中不同长度的K回文子串的数量计算问题,通过区间动态规划的方法高效地实现了这一目标。

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