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Commit 43b4bd7

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Distinct pairs done
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package com.leetcode.math;
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/**
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* Level: Easy
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* Problem Link: https://leetcode.com/problems/excel-sheet-column-number/
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* Problem Description:
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* Given a column title as appear in an Excel sheet, return its corresponding column number.
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*
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* For example:
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*
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* A -> 1
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* B -> 2
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* C -> 3
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* ...
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* Z -> 26
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* AA -> 27
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* AB -> 28
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* ...
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*
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* Example 1:
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* Input: "A"
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* Output: 1
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*
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* Example 2:
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* Input: "AB"
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* Output: 28
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*
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* Example 3:
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* Input: "ZY"
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* Output: 701
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*
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* @author rampatra
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* @since 2019年05月31日
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*/
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public class ExcelSheetColumnNumber {
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private static int titleToNumber(String title) {
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return 0;
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}
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public static void main(String[] args) {
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}
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}
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package com.rampatra.arrays;
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import java.util.HashSet;
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import java.util.Set;
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/**
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* Level: Easy
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* Problem Description:
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* Given an array and a target sum, return the number of distinct pairs whose sum is equal to the target sum.
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* <p>
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* For Example, given an array [1, 2, 3, 6, 7, 8, 9, 1] and a target sum of 10,
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* the 7 pairs, i.e, (1, 9), (2, 8), (3, 7), (8, 2), (9, 1), (9, 1), and (1, 9) all sum to 10 but there are only
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* three distinct pairs, i.e, (1, 9), (2, 8), and (3, 7) so the answer would be 3.
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*
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* @author rampatra
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* @since 2019年06月03日
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*/
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public class DistinctPairs {
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/**
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* Time complexity: O(n), n = size of the array
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* Space complexity: O(n)
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*
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* @param arr
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* @param targetSum
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* @return
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*/
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private static int numberOfDistinctPairs(int[] arr, int targetSum) {
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Set<Integer> numSet = new HashSet<>();
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Set<Set<Integer>> pairSet = new HashSet<>();
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for (int i = 0; i < arr.length; i++) {
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if (numSet.contains(targetSum - arr[i])) {
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Set<Integer> pair = new HashSet<>();
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pair.add(arr[i]);
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pair.add(targetSum - arr[i]);
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pairSet.add(pair);
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}
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numSet.add(arr[i]);
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}
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return pairSet.size();
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}
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public static void main(String[] args) {
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System.out.println(numberOfDistinctPairs(new int[]{1, 2, 3, 6, 7, 8, 9, 1}, 1));
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System.out.println(numberOfDistinctPairs(new int[]{1, 2, 3, 6, 7, 8, 9, 1}, 2));
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System.out.println(numberOfDistinctPairs(new int[]{1, 2, 3, 6, 7, 8, 9, 1}, 10));
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}
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}

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