
ZOJ Problem Set  3985
BaoBao has just found a string \(s\) of length \(n\) consisting of 'C' and 'P' in his pocket. As a big fan of the China Collegiate Programming Contest, BaoBao thinks a substring \(s_is_{i+1}s_{i+2}s_{i+3}\) of \(s\) is "good", if and only if \(s_i = s_{i+1} = s_{i+3} =\) 'C', and \(s_{i+2} =\) 'P', where \(s_i\) denotes the \(i\)th character in string \(s\). The value of \(s\) is the number of different "good" substrings in \(s\). Two "good" substrings \(s_is_{i+1}s_{i+2}s_{i+3}\) and \(s_js_{j+1}s_{j+2}s_{j+3}\) are different, if and only if \(i \ne j\). To make this string more valuable, BaoBao decides to buy some characters from a character store. Each time he can buy one 'C' or one 'P' from the store, and insert the character into any position in \(s\). But everything comes with a cost. If it's the \(i\)th time for BaoBao to buy a character, he will have to spend \(i1\) units of value. The final value BaoBao obtains is the final value of \(s\) minus the total cost of all the characters bought from the store. Please help BaoBao maximize the final value. InputThere are multiple test cases. The first line of the input contains an integer \(T\), indicating the number of test cases. For each test case: The first line contains an integer \(n\) (\(1 \le n \le 2\times 10^5\)), indicating the length of string \(s\). The second line contains the string \(s\) (\(s = n\)) consisting of 'C' and 'P'. It's guaranteed that the sum of \(n\) over all test cases will not exceed \(10^6\). OutputFor each test case output one line containing one integer, indicating the maximum final value BaoBao can obtain. Sample Input3 3 CCC 5 CCCCP 4 CPCP Sample Output1 1 1 HintFor the first sample test case, BaoBao can buy one 'P' (cost 0 value) and change \(s\) to "CCPC". So the final value is 1  0 = 1. For the second sample test case, BaoBao can buy one 'C' and one 'P' (cost 0 + 1 = 1 value) and change \(s\) to "CCPCCPC". So the final value is 2  1 = 1. For the third sample test case, BaoBao can buy one 'C' (cost 0 value) and change \(s\) to "CCPCP". So the final value is 1  0 = 1. It's easy to prove that no strategies of buying and inserting characters can achieve a better result for the sample test cases. Author: WENG, Caizhi Source: The 2017 China Collegiate Programming Contest, Qinhuangdao Site 