package q761

func toNumber(arrs ...[]byte) int {
	r := 0
	for i := range arrs {
		for _, num := range arrs[i] {
			r = r<<1 + int(num)
		}
	}
	return r
}

func fromNumber(arr []byte, num int) {
	for i := len(arr) - 1; i >= 0; i-- {
		arr[i] = byte(num % 2)
		num >>= 1
	}
}

func move(arr []byte) int {
	specials := [][2]int{}
	specialsMap := make(map[int][]int, len(arr)+1)
	val := toNumber(arr)

	for i := range len(arr) - 1 {
		if arr[i] == 0 {
			continue
		}
		bal := 1
		for j := i + 1; j < len(arr); j++ {
			switch arr[j] {
			case 0:
				bal--
			case 1:
				bal++
			}

			if bal < 0 {
				break
			}
			if bal == 0 {
				specials = append(specials, [2]int{i, j})
				specialsMap[i] = append(specialsMap[i], j)
			}
		}
	}

	for i := range specials {
		l1, r1 := specials[i][0], specials[i][1]
		l2 := r1 + 1
		for _, r2 := range specialsMap[l2] {
			swapped := toNumber(arr[:l1], arr[l2:r2+1], arr[l1:l2], arr[r2+1:])
			if swapped > val {
				val = swapped
			}
		}
	}
	return val
}

func makeLargestSpecial(s string) string {
	arr := []byte(s)
	for i := range arr {
		arr[i] -= '0'
	}

	val := toNumber(arr)
	for {
		newVal := move(arr)
		if newVal > val {
			val = newVal
			fromNumber(arr, newVal)
		} else {
			break
		}
	}

	for i := range arr {
		arr[i] += '0'
	}
	return string(arr)
}

var _ = makeLargestSpecial