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[LeetCode] 13. Roman to Integer

13. Roman to Integer Easy 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 ones added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II. Roman numerals are usually written largest to smallest f..

[LeetCode] 242. Valid Anagram

242. Valid Anagram Easy Given two strings s and t, return true if t is an anagram of s, and false otherwise. An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once. Example 1: Input: s = "anagram", t = "nagaram" Output: true Example 2: Input: s = "rat", t = "car" Output: false Constraints: 1 bool: # ha..

[LeetCode] 531. Lonely Pixel I

531. Lonely Pixel I Medium Given an m x n picture consisting of black 'B' and white 'W' pixels, return the number of black lonely pixels. A black lonely pixel is a character 'B' that located at a specific position where the same row and same column don't have any other black pixels. Example 1: Input: picture = [["W","W","B"],["W","B","W"],["B","W","W"]] Output: 3 Explanation: All the three 'B's ..