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Commit 788eb3d

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binary search questions: done
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package com.leetcode.arrays.binarysearch;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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/**
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* Level: Easy
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* Link: https://leetcode.com/problems/search-insert-position/
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* Description:
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* Given a sorted array and a target value, return the index if the target is found. If not, return the index where it
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* would be if it were inserted in order.
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* <p>
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* You may assume no duplicates in the array.
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* <p>
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* Example 1:
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* Input: [1,3,5,6], 5
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* Output: 2
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* <p>
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* Example 2:
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* Input: [1,3,5,6], 2
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* Output: 1
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* <p>
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* Example 3:
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* Input: [1,3,5,6], 7
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* Output: 4
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* <p>
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* Example 4:
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* Input: [1,3,5,6], 0
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* Output: 0
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*
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* Similar question: {@link SmallestLetterGreaterThanTarget}.
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*
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* @author rampatra
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* @since 2019年08月19日
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*/
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public class SearchInsertPosition {
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/**
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* Runtime: <a href="https://leetcode.com/submissions/detail/253066747/">0 ms</a>.
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*
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* @param nums
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* @param target
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* @return
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*/
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public static int searchInsert(int[] nums, int target) {
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int low = 0;
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int high = nums.length - 1;
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while (low <= high) {
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int mid = low + (high - low) / 2;
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if (nums[mid] == target) {
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return mid;
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} else if (nums[mid] < target) {
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low = mid + 1;
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} else {
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high = mid - 1;
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}
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}
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return low;
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}
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public static void main(String[] args) {
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assertEquals(2, searchInsert(new int[]{1, 2}, 3));
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}
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}
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package com.leetcode.arrays.binarysearch;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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/**
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* Level: Easy
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* Link: https://leetcode.com/problems/find-smallest-letter-greater-than-target/
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* Description:
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* Given a list of sorted characters letters containing only lowercase letters, and given a target letter target, find
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* the smallest element in the list that is larger than the given target.
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*
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* Letters also wrap around. For example, if the target is target = 'z' and letters = ['a', 'b'], the answer is 'a'.
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*
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* Examples:
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*
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* Input:
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* letters = ["c", "f", "j"]
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* target = "a"
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* Output: "c"
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*
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* Input:
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* letters = ["c", "f", "j"]
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* target = "c"
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* Output: "f"
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*
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* Input:
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* letters = ["c", "f", "j"]
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* target = "d"
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* Output: "f"
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*
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* Input:
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* letters = ["c", "f", "j"]
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* target = "g"
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* Output: "j"
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*
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* Input:
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* letters = ["c", "f", "j"]
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* target = "j"
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* Output: "c"
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*
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* Input:
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* letters = ["c", "f", "j"]
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* target = "k"
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* Output: "c"
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*
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* Note:
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* - letters has a length in range [2, 10000].
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* - letters consists of lowercase letters, and contains at least 2 unique letters.
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* - target is a lowercase letter.
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*
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* @author rampatra
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* @since 2019年08月19日
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*/
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public class SmallestLetterGreaterThanTarget {
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/**
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* Runtime: <a href="https://leetcode.com/submissions/detail/253061487/">0 ms</a>.
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*
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* @param letters
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* @param target
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* @return
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*/
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public static char nextGreatestLetter(char[] letters, char target) {
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int low = 0, hi = letters.length - 1;
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while (low <= hi) {
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int mid = low + (hi - low) / 2;
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if (letters[mid] <= target) {
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low = mid + 1;
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} else {
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hi = mid - 1;
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}
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}
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return letters[low % letters.length];
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}
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public static void main(String[] args) {
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assertEquals('a', nextGreatestLetter(new char[]{'a'}, 'z'));
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assertEquals('b', nextGreatestLetter(new char[]{'a', 'b'}, 'a'));
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assertEquals('b', nextGreatestLetter(new char[]{'a', 'b', 'c'}, 'a'));
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assertEquals('a', nextGreatestLetter(new char[]{'a', 'b', 'c'}, 'z'));
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assertEquals('c', nextGreatestLetter(new char[]{'c', 'f', 'j'}, 'a'));
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assertEquals('f', nextGreatestLetter(new char[]{'c', 'f', 'j'}, 'c'));
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assertEquals('f', nextGreatestLetter(new char[]{'c', 'f', 'j'}, 'd'));
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assertEquals('b', nextGreatestLetter(new char[]{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'l',
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'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}, 'a'));
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}
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}

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