Sliding-Window

An integer has sequential digits if and only if each digit in the number is one more than the previous digit. Return a sorted list of all the integers in the range [low, high] inclusive that have sequential digits. Example 1: Input: low = 100, high = 300 Output: [123,234] Example 2: Input: low = 1000, high = 13000 Output: [1234,2345,3456,4567,5678,6789,12345] Constraints: 10 <= low <= high <= 10^9 Solution Sliding Window class Solution { public List<Integer> sequentialDigits(int lo, int hi) { int lenLo = getLen(lo); int lenHi = getLen(hi); int i = lenLo; List<Integer> res = new ArrayList<>(); while (i <= lenHi) { res.addAll(buildSeqNums(i, lo, hi)); i++; } return res; } int getLen(int n) { return Integer.toString(n).length(); } String SAMPLE = "123456789"; List<Integer> buildSeqNums(int n, int lo, int hi) { if (n == 0) return Collections.emptyList(); int start = 0; List<Integer> res = new ArrayList<>(); while (start + n < SAMPLE.length() + 1) { int val = Integer.parseInt(SAMPLE.substring(start, start + n)); if (val >= lo && val <= hi) { res.add(val); } start++; } return res; } }

There are several cards arranged in a row, and each card has an associated number of points. The points are given in the integer array cardPoints. In one step, you can take one card from the beginning or from the end of the row. You have to take exactly k cards. Your score is the sum of the points of the cards you have taken. ...

11004. Max Consecutive Ones III Given a binary array nums and an integer k, return the maximum number of consecutive 1’s in the array if you can flip at most k 0’s. Example 1: Input: nums = [1,1,1,0,0,0,1,1,1,1,0], k = 2 Output: 6 Explanation: [1,1,1,0,0,1,1,1,1,1,1] Bolded numbers were flipped from 0 to 1. The longest subarray is underlined. Example 2: Input: nums = [0,0,1,1,0,0,1,1,1,0,1,1,0,0,0,1,1,1,1], k = 3 Output: 10 Explanation: [0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,1,1,1,1] Bolded numbers were flipped from 0 to 1. The longest subarray is underlined. Constraints: ...

159. Longest Substring with At Most Two Distinct Characters Given a string s, return the length of the longest substring that contains at most two distinct characters. Example 1: Input: s = "eceba" Output: 3 Explanation: The substring is "ece" which its length is 3. Example 2: Input: s = "ccaabbb" Output: 5 Explanation: The substring is "aabbb" which its length is 5. Constraints: 1 <= s.length <= 104 s consists of English letters. Solution class Solution { public int lengthOfLongestSubstringTwoDistinct(String s) { int start = 0; int end = 0; int maxLen = 0; int uniq = 0; int[] map = new int[128]; while (end < s.length()) { char c = s.charAt(end); map[c]++; if (map[c] == 1) uniq++; end++; while (uniq > 2) { char prev = s.charAt(start); map[prev]--; if (map[prev] == 0) uniq--; start++; } maxLen = Math.max(maxLen, end - start); } return maxLen; } }

209. Minimum Size Subarray Sum Given an array of positive integers nums and a positive integer target, return the minimal length of a contiguous subarray [numsl, numsl+1, …, numsr-1, numsr] of which the sum is greater than or equal to target. If there is no such subarray, return 0 instead. Example 1: Input: target = 7, nums = [2,3,1,2,4,3] Output: 2 Explanation: The subarray [4,3] has the minimal length under the problem constraint. Example 2: Input: target = 4, nums = [1,4,4] Output: 1 Example 3: Input: target = 11, nums = [1,1,1,1,1,1,1,1] Output: 0 Constraints: ...

3. Longest Substring Without Repeating Characters Given a string s, find the length of the longest substring without repeating characters. Example 1: Input: s = "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Example 2: Input: s = "bbbbb" Output: 1 Explanation: The answer is "b", with the length of 1. Example 3: Input: s = "pwwkew" Output: 3 Explanation: The answer is "wke", with the length of 3. Notice that the answer must be a substring, "pwke" is a subsequence and not a substring. Example 4: Input: s = "" Output: 0 Constraints: ...

424. Longest Repeating Character Replacement You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform this operation at most k times. Return the length of the longest substring containing the same letter you can get after performing the above operations. Example 1: Input: s = "ABAB", k = 2 Output: 4 Explanation: Replace the two 'A's with two 'B's or vice versa. Example 2: Input: s = "AABABBA", k = 1 Output: 4 Explanation: Replace the one 'A' in the middle with 'B' and form "AABBBBA". The substring "BBBB" has the longest repeating letters, which is 4. Constraints: ...

340. Longest Substring with At Most K Distinct Characters Given a string s and an integer k, return the length of the longest substring of s that contains at most k distinct characters. Example 1: Input: s = "eceba", k = 2 Output: 3 Explanation: The substring is "ece" with length 3. Example 2: Input: s = "aa", k = 1 Output: 2 Explanation: The substring is "aa" with length 2. Constraints: ...

76. Minimum Window Substring Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is included in the window. If there is no such substring, return the empty string “”. The testcases will be generated such that the answer is unique. A substring is a contiguous sequence of characters within the string. Example 1: Input: s = "ADOBECODEBANC", t = "ABC" Output: "BANC" Explanation: The minimum window substring "BANC" includes 'A', 'B', and 'C' from string t. Example 2: Input: s = "a", t = "a" Output: "a" Explanation: The entire string s is the minimum window. Example 3: Input: s = "a", t = "aa" Output: "" Explanation: Both 'a's from t must be included in the window. Since the largest window of s only has one 'a', return empty string. Constraints: ...

1852. Distinct Numbers in Each Subarray Given an integer array nums and an integer k, you are asked to construct the array ans of size n-k+1 where ans[i] is the number of distinct numbers in the subarray nums[i:i+k-1] = [nums[i], nums[i+1], …, nums[i+k-1]]. Return the array ans. Example 1: Input: nums = [1,2,3,2,2,1,3], k = 3 Output: [3,2,2,2,3] Explanation: The number of distinct elements in each subarray goes as follows: - nums[0:2] = [1,2,3] so ans[0] = 3 - nums[1:3] = [2,3,2] so ans[1] = 2 - nums[2:4] = [3,2,2] so ans[2] = 2 - nums[3:5] = [2,2,1] so ans[3] = 2 - nums[4:6] = [2,1,3] so ans[4] = 3 Example 2: Input: nums = [1,1,1,1,2,3,4], k = 4 Output: [1,2,3,4] Explanation: The number of distinct elements in each subarray goes as follows: - nums[0:3] = [1,1,1,1] so ans[0] = 1 - nums[1:4] = [1,1,1,2] so ans[1] = 2 - nums[2:5] = [1,1,2,3] so ans[2] = 3 - nums[3:6] = [1,2,3,4] so ans[3] = 4 Constraints: ...