package q3719

var seen [6000]bool

func longestBalanced(nums []int) int {
	// Map numbers to reduce the range
	mapped := make(map[int]int, len(nums))
	nextEven, nextOdd := 0, 1
	for i := range nums {
		if m, ok := mapped[nums[i]]; ok {
			nums[i] = m
		} else if nums[i]%2 == 0 {
			mapped[nums[i]] = nextEven
			nums[i] = nextEven
			nextEven += 2
		} else {
			mapped[nums[i]] = nextOdd
			nums[i] = nextOdd
			nextOdd += 2
		}
	}
	numRange := max(nextEven, nextOdd)
	copy(seen[:3000], seen[3000:]) // init

	longest := 0
	for i := 1; i < len(nums); i++ {
		copy(seen[:numRange], seen[numRange:]) // reset
		odd, even := 0, 0
		for j := i; j >= 0; j-- {
			num := nums[j]
			if seen[num] {
				if even == odd {
					longest = max(longest, i-j+1)
				}
				continue
			}
			seen[num] = true

			if num%2 == 0 {
				even++
			} else {
				odd++
			}
			if even == odd {
				longest = max(longest, i-j+1)
			}
		}
	}

	return longest
}

var _ = longestBalanced