The bear has a string s = s1s2... s|s| (record |s| is the string's length), consisting of lowercase English letters. The bear wants to count the number of such pairs of indices i, j (1 ≤ i ≤ j ≤ |s|), that string x(i, j) = sisi + 1... sj contains at least one string "bear" as a substring.
String x(i, j) contains string "bear", if there is such index k (i ≤ k ≤ j - 3), that sk = b, sk + 1 = e, sk + 2 = a, sk + 3 = r.
Help the bear cope with the given problem.
The first line contains a non-empty string s (1 ≤ |s| ≤ 5000). It is guaranteed that the string only consists of lowercase English letters.
Print a single number — the answer to the problem.
bearbtear
6
bearaabearc
20
In the first sample, the following pairs (i, j) match: (1, 4), (1, 5), (1, 6), (1, 7), (1, 8), (1, 9).
In the second sample, the following pairs (i, j) match: (1, 4), (1, 5), (1, 6), (1, 7), (1, 8), (1, 9), (1, 10), (1, 11), (2, 10), (2, 11), (3, 10), (3, 11), (4, 10), (4, 11), (5, 10), (5, 11), (6, 10), (6, 11), (7, 10), (7, 11).
#include <iostream> #include <string> #include <stdio.h> #include <vector> #include <algorithm> using namespace std; int gao(string s){ vector< pair<int,int> >seg ; vector< pair<int,int> >::iterator it ; seg.clear() ; int i ,Len = s.length() ,L ,R ,ans = 0 ,reL ; for(i = 0 ; i <= Len - 4 ; i++){ if(s[i]=='b'&&s[i+1]=='e'&&s[i+2]=='a'&&s[i+3]=='r') seg.push_back(make_pair(i+1,i+1+3)) ; } if(seg.size() == 0) return 0 ; it = seg.begin() ; reL = L = it->first ; R = it->second ; ans += L * (Len - R +1) ; for(it++; it != seg.end() ; it++){ L = it->first ; R = it->second ; ans += (L - reL) * (Len - R + 1) ; reL = L ; } return ans ; } int main(){ string s ; while(cin>>s){ cout<<gao(s)<<endl ; } return 0 ; }