You've got a string s = s1s2... s|s| of length |s|, consisting of lowercase English letters. There also are q queries, each query is described by two integers li, ri (1 ≤ li ≤ ri ≤ |s|). The answer to the query is the number of substrings of string s[li... ri], which are palindromes.
String s[l... r] = slsl + 1... sr (1 ≤ l ≤ r ≤ |s|) is a substring of string s = s1s2... s|s|.
String t is called a palindrome, if it reads the same from left to right and from right to left. Formally, if t = t1t2... t|t| = t|t|t|t| - 1... t1.
The first line contains string s (1 ≤ |s| ≤ 5000). The second line contains a single integer q (1 ≤ q ≤ 106) — the number of queries. Next q lines contain the queries. The i-th of these lines contains two space-separated integers li, ri (1 ≤ li ≤ ri ≤ |s|) — the description of the i-th query.
It is guaranteed that the given string consists only of lowercase English letters.
Print q integers — the answers to the queries. Print the answers in the order, in which the queries are given in the input. Separate the printed numbers by whitespaces.
caaaba
5
1 1
1 4
2 3
4 6
4 5
1
7
3
4
2
Consider the fourth query in the first test case. String s[4... 6] = «aba». Its palindrome substrings are: «a», «b», «a», «aba».
代码:
#include<stdio.h> #include<string.h> int dp[5010][5010],and1[5010][5010]; int main() { char s[5010]; int q,l,r,sta,end,len; int i; gets(s); len=strlen(s); for(i=0; i<len; i++) { dp[i][i]=and1[i][i]=1; and1[i+1][i]=1; } for(i=2;i<=len;i++) for(sta=0;sta<len;sta++) { end=sta+i-1; if(and1[sta+1][end-1]&&s[sta]==s[end]) and1[sta][end]=1; dp[sta][end]=dp[sta+1][end]+dp[sta][end-1]-dp[sta+1][end-1]+and1[sta][end]; } scanf("%d",&q); while(q--) { scanf("%d %d",&l,&r); printf("%d ",dp[l-1][r-1]); } return 0; }