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anishLearnsToCodeanishLearnsToCode
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solves #380: Insert Delete GetRandom O(1) in java
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-53
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3 files changed

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Diff for: ‎README.md

+1
Original file line numberDiff line numberDiff line change
@@ -292,6 +292,7 @@
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| 359 | 🔒 [Logger Rate Limiter](https://leetcode.com/problems/logger-rate-limiter) | | |
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| 367 | [Valid Perfect Square](https://leetcode.com/problems/valid-perfect-square) | [![Java](assets/java.png)](src/IsPerfectSquare.java) [![Python](assets/python.png)](python/valid_perfect_square.py) | |
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| 374 | [Guess Number Higher or Lower](https://leetcode.com/problems/guess-number-higher-or-lower) | [![Java](assets/java.png)](src/GuessNumberHigherOrLower.java) [![Python](assets/python.png)](python/guess_number_higher_or_lower.py) | |
295+
| 380 | [Insert Delete GetRandom O(1)](https://leetcode.com/problems/insert-delete-getrandom-o1) | [![Java](assets/java.png)](src/InsertDeleteGetRandomO1.java) | |
295296
| 383 | [Ransom Note](https://leetcode.com/problems/ransom-note) | [![Java](assets/java.png)](src/RansomNote.java) [![Python](assets/python.png)](python/ransom_note.py) | |
296297
| 387 | [First Unique Character in String](https://leetcode.com/problems/first-unique-character-in-a-string) | [![Java](assets/java.png)](src/FirstUniqueCharacter.java) [![Python](assets/python.png)](python/first_unique_character_in_string.py) | |
297298
| 389 | [Find the Difference](https://leetcode.com/problems/find-the-difference) | [![Java](assets/java.png)](src/FindTheDifference.java) [![Python](assets/python.png)](python/find_the_difference.py) | |

Diff for: ‎src/HelloWorld.java

+27-53
Original file line numberDiff line numberDiff line change
@@ -1,65 +1,39 @@
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import java.util.Scanner;
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import java.util.*;
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public class HelloWorld {
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private static final Scanner SCANNER = new Scanner(System.in);
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private static void spiralOrder(int[][] matrix){
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final int rows = matrix.length, columns = matrix[0].length, elements = rows * columns;
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for (int i = 0, top = 0, bottom = rows, left = 0, right = columns ; ; ) {
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for (int row = top, column = left ; column < right ; column++, i++) {
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System.out.print(matrix[row][column]);
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}
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top++;
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if (i == elements) break;
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for (int row = top, column = right - 1 ; row < bottom ; row++, i++) {
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System.out.print(matrix[row][column]);
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}
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right--;
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if (i == elements) break;
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for (int row = bottom - 1, column = right - 1 ; column >= left ; column--, i++) {
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System.out.print(matrix[row][column]);
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}
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bottom--;
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if (i == elements) break;
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for (int row = bottom - 1, column = left ; row >= top ; row--, i++) {
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System.out.print(matrix[row][column]);
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static class RandomizedSet {
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private final Random random = new Random();
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private final List<Integer> list = new ArrayList<>();
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private final Map<Integer, Integer> indexMapping = new HashMap<>();
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public boolean insert(int val) {
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if (indexMapping.containsKey(val)) {
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return false;
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}
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left++;
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if (i == elements) break;
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list.add(val);
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indexMapping.put(val, list.size() - 1);
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return true;
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}
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}
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private static int intInput(final String string) {
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System.out.print(string);
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final int i = SCANNER.nextInt();
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return i;
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}
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private static void print(int[][] matrix) {
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for (int[] row : matrix) {
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for (int element : row) {
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System.out.print(element + " ");
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}
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System.out.println();
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private int last() {
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return this.list.getLast();
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}
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}
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public static void main(String[] args) {
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final int rows = intInput("Enter row size: ");
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final int columns = intInput("Enter column size: ");
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final int[][] matrix = new int[rows][columns];
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52-
System.out.println("Enter array elements:");
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54-
for (int i = 0 ; i < rows ; i++) {
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for(int j = 0 ; j < columns ; j++) {
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matrix[i][j] = SCANNER.nextInt();
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public boolean remove(int val) {
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if (!indexMapping.containsKey(val)) {
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return false;
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}
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final int index = indexMapping.get(val);
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indexMapping.put(last(), index);
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indexMapping.remove(val);
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list.set(index, last());
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list.removeLast();
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return true;
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}
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60-
spiralOrder(matrix);
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System.out.println("\n\nOriginal matrix");
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print(matrix);
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public int getRandom() {
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final int randomIndex = random.nextInt(list.size());
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return list.get(randomIndex);
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}
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}
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}

Diff for: ‎src/InsertDeleteGetRandomO1.java

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,45 @@
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// https://leetcode.com/problems/insert-delete-getrandom-o1
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.Random;
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9+
public class InsertDeleteGetRandomO1 {
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static class RandomizedSet {
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private final Random random = new Random();
12+
private final List<Integer> list = new ArrayList<>();
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private final Map<Integer, Integer> indexMapping = new HashMap<>();
14+
15+
public boolean insert(int val) {
16+
if (indexMapping.containsKey(val)) {
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return false;
18+
}
19+
list.add(val);
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indexMapping.put(val, list.size() - 1);
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return true;
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}
23+
24+
private int last() {
25+
return this.list.getLast();
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}
27+
28+
public boolean remove(int val) {
29+
if (!indexMapping.containsKey(val)) {
30+
return false;
31+
}
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final int index = indexMapping.get(val);
33+
indexMapping.put(last(), index);
34+
indexMapping.remove(val);
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list.set(index, last());
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list.removeLast();
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return true;
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}
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40+
public int getRandom() {
41+
final int randomIndex = random.nextInt(list.size());
42+
return list.get(randomIndex);
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}
44+
}
45+
}

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