--# https://theweeklychallenge.org/blog/perl-weekly-challenge-342/
--[[

Task 2: Max Score

Submitted by: [47]Mohammad Sajid Anwar
     __________________________________________________________________

   You are given a string, $str, containing 0 and 1 only.

   Write a script to return the max score after splitting the string into
   two non-empty substrings. The score after splitting a string is the
   number of zeros in the left substring plus the number of ones in the
   right substring.

Example 1

Input: $str = "0011"
Output: 4

1: left = "0", right = "011" => 1 + 2 => 3
2: left = "00", right = "11" => 2 + 2 => 4
3: left = "001", right = "1" => 2 + 1 => 3

Example 2

Input: $str = "0000"
Output: 3

1: left = "0", right = "000" => 1 + 0 => 1
2: left = "00", right = "00" => 2 + 0 => 2
3: left = "000", right = "0" => 3 + 0 => 3

Example 3

Input: $str = "1111"
Output: 3

1: left = "1", right = "111" => 0 + 3 => 3
2: left = "11", right = "11" => 0 + 2 => 2
3: left = "111", right = "1" => 0 + 1 => 1

Example 4

Input: $str = "0101"
Output: 3

1: left = "0", right = "101" => 1 + 2 => 3
2: left = "01", right = "01" => 1 + 1 => 2
3: left = "010", right = "1" => 2 + 1 => 3

Example 5

Input: $str = "011101"
Output: 5

1: left = "0", right = "11101" => 1 + 4 => 5
2: left = "01", right = "1101" => 1 + 3 => 4
3: left = "011", right = "101" => 1 + 2 => 3
4: left = "0111", right = "01" => 1 + 1 => 2
5: left = "01110", right = "1" => 2 + 1 => 3
     __________________________________________________________________

   Last date to submit the solution 23:59 (UK Time) Sunday 12th October
   2025.
     __________________________________________________________________

SO WHAT DO YOU THINK ?
--]]
--# solution by pokgopun@gmail.com

--@param str string
--@return number
function ms(str)
	local off = {}
	local sm = 0
	string.gsub(
		str,
		".",
		function (s)
			local b = s == "1"
			if not b then
				sm = sm + 1
			end
			table.insert(off,b)
		end)
	local mx = 0
	for i=#off, 2, -1 do
		if off[i] then
			sm = sm + 1
		else
			sm = sm - 1
		end
		if mx < sm then
			mx = sm
		end
	end
	return mx
end

local lu = require("luaunit")

function test()
	for _, data in ipairs({
		{Input = "0011", Output = 4},
		{Input = "0000", Output = 3},
		{Input = "1111", Output= 3},
		{Input = "0101",Output= 3},
		{Input = "011101",Output= 5}}) do
		lu.assertEquals(ms(data.Input), data.Output)
	end
end

lu.run()