Sliding Window

O(n)
n = size(array)

Python: Shrinkable | Java: Shrinkable

	# i
	# nums: [5,7,2,8]
	# j
	def longestWindow(nums: List[int]) -> int:
	j = 0, ans
	for i in range(nums):
	# code using nums[i] to update the state
	# that might invalidate the window
	while invalid():
	# code using nums[j] to update the state
	# and shrink the left edge while the window is invalid
	j += 1
	# longest window so far = len([i, j])
	ans = max(ans, i - j + 1);
	return ans

view raw longestWindow-shrinkable.py hosted with ❤ by GitHub

	// i
	// nums: [5,7,2,8]
	// j
	int longestWindow(int[] nums) {
	int max;
	for (int i = 0, j = 0; i < nums.length; i++) {
	// code using nums[i] to update the state
	// that might invalidate the window
	for (; invalid(); j++) {
	// code using nums[j] to update the state
	// and shrink the left edge while the window is invalid
	}
	// longest window so far = length([i, j])
	max = max(ans, i - j + 1);
	}
	return max;
	}

view raw longestWindow-shrinkable.java hosted with ❤ by GitHub

Python: Non-shrinkable | Java: Non-shrinkable

	# i
	# nums: [5,7,2,8]
	# j
	def longestWindow(nums: List[int]) -> int:
	i = j = 0;
	for i in range(nums):
	# code using nums[i] to update the state
	# that might invalidate the window
	if invalid():
	# code using nums[j] to update the state
	# and shift the window sideways.
	# the window grows if the state is valid
	# and shifts if it's invalid.
	j += 1
	# the maximum size of the window
	return i - j

view raw longestWindow-nonshrinkable.py hosted with ❤ by GitHub

	// i
	// nums: [5,7,2,8]
	// j
	int longestWindow(int[] nums) {
	int i = 0, j = 0;
	for (; i < nums.length; i++) {
	// code using nums[i] to update the state
	// that might invalidate the window
	if (invalid()) {
	// code using nums[j] to update the state
	// and shift the window sideways.
	// the window grows if the state is valid
	// and shifts if it's invalid.
	j++;
	}
	}
	return i - j; // the maximum size of the window
	}

view raw longestWindow-nonshrinkable.java hosted with ❤ by GitHub