Find Max Slice Array | Javascript

Question

I need to find the maximum slice of an array that contains no more than two different numbers.

Here is my array [1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 6, 2, 1, 8]

My thought process is to find numbers that don't repeat and return their index to a new array.

Here is what I still have:

 function goThroughInteger(number) { var array = []; //iterate the array and check if number is not repeated number.filter(function (element, index, number) { if(element != number[index-1] && element != number[index+1]) { array.push(index); return element; } }) console.log(array); } goThroughInteger([1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 6, 2, 1, 8]); 

I'm not sure where to go next, I struggle to understand the question of what it is - to find the maximum cut that contains no more than two different numbers - it bothers me.

Answer 1

A one-cycle solution that checks the latest values ​​and increments the counter.

 function getLongestSlice(array) { var count = 0, max = 0, temp = []; array.forEach(function (a) { var last = temp[temp.length - 1]; if (temp.length < 2 || temp[0].value === a || temp[1].value === a) { ++count; } else { count = last.count + 1; } if (last && last.value === a) { last.count++; } else { temp.push({ value: a, count: 1 }); temp = temp.slice(-2); } if (count > max) { max = count; } }); return max; } console.log(getLongestSlice([58, 800, 0, 0, 0, 356, 8988, 1, 1])); // 4 console.log(getLongestSlice([58, 800, 0, 0, 0, 356, 356, 8988, 1, 1])); // 5 console.log(getLongestSlice([1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 6, 2, 1, 8])); // 10 

Answer 2

This is a possible solution with complexity O (n²) (as pointed out by @le_m in comments)

 goThroughInteger = list => { let scores = list.reduce((slices, num, pos) => { let valid = [num] let count = 0; for (let i=pos; i<list.length; i++) { if (valid.indexOf(list[i]) == -1) { if (valid.length < 2) { valid.push(list[i]) count++ } else { break } } else { count++ } } slices[pos] = {pos, count} return slices }, []) scores.sort((a,b) => b.count - a.count) let max = scores[0] return list.slice(max.pos, max.pos + max.count) } console.log(goThroughInteger([1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 6, 2, 1, 8])) console.log(goThroughInteger([58, 800, 0, 0, 0, 356, 8988, 1, 1])) 

It calculates the “score” at each position in the input list, counting the length of the sequence of no more than two different values. Then it gets the result with the highest result and extracts a fragment from the original list based on this information.

It can definitely be cleaned and optimized, but I think this is a good starting point.

Answer 3

  function goThroughInteger(array) { var solutionArray = []; var max = 0; for (var i = 0; i <= array.length; i++) { for (var j = i + 1; j <= array.length; j++) { var currentSlice= array.slice(i,j); var uniqSet = [...new Set(currentSlice)]; if(uniqSet.length <3) { if(currentSlice.length>max) { max= currentSlice.length; } } } } console.log(max); } goThroughInteger([1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 6, 2, 1, 8]); 

This solution checks all possible fragments of the array, checks to see if it has at most two different numbers, and finally displays the length of the longest fragment.