Medium

240. Search a 2D Matrix II Write an efficient algorithm that searches for a target value in an m x n integer matrix. The matrix has the following properties: Integers in each row are sorted in ascending from left to right. Integers in each column are sorted in ascending from top to bottom. Example 1: Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5 Output: true Example 2: Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20 Output: false ...

74. Search a 2D Matrix Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted from left to right. The first integer of each row is greater than the last integer of the previous row. Example 1: Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3 Output: true Example 2: Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13 Output: false ...

Wine Selling Problem Problem statement: Given n wines in a row, with integers denoting the cost of each wine respectively. Each year you can sell the first or the last wine in the row. Let the initial profits from the wines be P1, P2, P3…Pn. In the Yth year, the profit from the ith wine will be Y*P[i]. The goal is to calculate the maximum profit that can be earned by selling all the wines. ...

12. Integer to Roman Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, 2 is written as II in Roman numeral, just two one’s added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II. ...

50. Pow(x, n) Implement pow(x, n), which calculates x raised to the power n (i.e., xn). Example 1: Input: x = 2.00000, n = 10 Output: 1024.00000 Example 2: Input: x = 2.10000, n = 3 Output: 9.26100 Example 3: Input: x = 2.00000, n = -2 Output: 0.25000 Explanation: 2-2 = 1/22 = 1/4 = 0.25 Constraints: -100.0 < x < 100.0 -231 <= n <= 231-1 -104 <= xn <= 104 Solution class Solution { public double myPow(double x, int n) { long N = n; if (n < 0) { x = 1.0 / x; N = -N; } long i = N; double res = 1.0; double current = x; while (i > 0) { if (i % 2 == 1) { res = res * current; } current = current * current; i = i / 2; } return res; } } Solution 2021-11-19 class Solution { public double myPow(double x, int n) { long N = n; if (n < 0) { x = 1 / x; N = -N; } double ans = 1.0; for (long i = N; i > 0; i = i / 2) { if (i % 2 == 1) { ans = ans * x; } x = x * x; } return ans; } } Solution 2021-01-30 class Solution { public double myPow(double x, int n) { long m = n; if (m == 0) return 1; if (m < 0) { m = -m; x = 1 / x; } double base = x; long degree = 1L; while (degree < m) { x = x * x; degree *= 2; } while (degree-- != m) { x /= base; } return x; } }

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: ...

11. Container With Most Water Given n non-negative integers a1, a2, …, an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of the line i is at (i, ai) and (i, 0). Find two lines, which, together with the x-axis forms a container, such that the container contains the most water. Notice that you may not slant the container. ...

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: ...