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Commit 2cb17d0

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solves #170: Two Sum III: Data structure design
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‎README.md

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| 167 | [Two Sum II - Input Array is Sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted) | [![Java](assets/java.png)](src/TwoSumIIInputArrayIsSorted.java) [![Python](assets/python.png)](python/two_sum_ii.py) | |
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| 168 | [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title) | [![Java](assets/java.png)](src/ExcelSheetColumnTitle.java) [![Python](assets/python.png)](python/excel_sheet_column_title.py) | |
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| 169 | [Majority Element](https://leetcode.com/problems/majority-element) | [![Java](assets/java.png)](src/MajorityElement.java) [![Python](assets/python.png)](python/majority_element.py) | |
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| 170 | 🔒 [Two Sum III - Data Structure Design](https://leetcode.com/problems/two-sum-iii-data-structure-design) | | |
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| 170 | 🔒 [Two Sum III - Data Structure Design](https://leetcode.com/problems/two-sum-iii-data-structure-design) | [![Java](assets/java.png)](src/TwoSumIIIDataStructureDesign.java) | |
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| 171 | [Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number) | [![Java](assets/java.png)](src/ExcelSheetColumnNumber.java) [![Python](assets/python.png)](python/excel_sheet_column_number.py) | |
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| 172 | [Factoring Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes) | [![Java](assets/java.png)](src/FactorialTrailingZeros.java) [![Python](assets/python.png)](python/factorial_trailing_zeroes.py) | |
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| 173 | [Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator) | [![Java](assets/java.png)](src/BinarySearchTreeIterator.java) | |

‎src/TwoSumIIIDataStructureDesign.java

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import java.util.HashMap;
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import java.util.Map;
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public class TwoSumIIIDataStructureDesign {
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static class TwoSum {
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private final Map<Integer, Integer> map = new HashMap<>();
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// T: O(1)
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public void add(int number) {
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map.put(number, map.getOrDefault(number, 0) + 1);
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}
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// N: number of unique elements we have seen so far
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// T: O(N)
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public boolean find(int sum) {
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for (int current : map.keySet()) {
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final int required = sum - current;
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if (required == current) {
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if (map.get(required) >= 2) {
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return true;
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} else {
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continue;
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}
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}
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if (map.containsKey(required)) {
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return true;
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}
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}
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return false;
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}
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}
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}

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