8000 add 788 · tes3906/Leetcode@addbe74 · GitHub
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‎README.md

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| # | Title | Solutions | Time | Space | Video | Difficulty | Tag
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|-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
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|788|[Rotated Digits](https://leetcode.com/problems/rotated-digits/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_788.java) | O(n*m) | O(1) | |Easy|
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|784|[Letter Case Permutation](https://leetcode.com/problems/letter-case-permutation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_784.java) | O(n*2^n) | O(n*2^n) | |Easy|
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|783|[Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_783.java) | O(n) | O(h) | |Easy|
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|779|[K-th Symbol in Grammar](https://leetcode.com/problems/k-th-symbol-in-grammar/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_779.java) | O(logn) | O(1) | |Medium|

‎src/main/java/com/fishercoder/solutions/_788.java

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package com.fishercoder.solutions;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* 788. Rotated Digits
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*
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* X is a good number if after rotating each digit individually by 180 degrees,
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* we get a valid number that is different from X.
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* A number is valid if each digit remains a digit after rotation.
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* 0, 1, and 8 rotate to themselves;
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* 2 and 5 rotate to each other;
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* 6 and 9 rotate to each other,
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* and the rest of the numbers do not rotate to any other number.
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Now given a positive number N, how many numbers X from 1 to N are good?
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Example:
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Input: 10
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Output: 4
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Explanation:
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There are four good numbers in the range [1, 10] : 2, 5, 6, 9.
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Note that 1 and 10 are not good numbers, since they remain unchanged after rotating.
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Note: N will be in range [1, 10000].
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*/
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public class _788 {
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public static class Solution1 {
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public int rotatedDigits(int N) {
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int count = 0;
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Map<Character, String> map = new HashMap<>();
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map.put('0', "0");
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map.put('1', "1");
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map.put('8', "8");
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map.put('2', "5");
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map.put('5', "2");
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map.put('6', "9");
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map.put('9', "6");
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for (int i = 1; i <= N; i++) {
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if (isRotatedNumber(i, map)) {
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count++;
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}
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}
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return count;
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}
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private boolean isRotatedNumber(int num, Map<Character, String> map) {
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String originalNum = String.valueOf(num);
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StringBuilder sb = new StringBuilder();
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for (char c : String.valueOf(num).toCharArray()) {
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if (!map.containsKey(c)) {
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return false;
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} else {
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sb.append(map.get(c));
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}
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}
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return !originalNum.equals(sb.toString());
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}
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}
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}

‎src/test/java/com/fishercoder/_788Test.java

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package com.fishercoder;
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import com.fishercoder.solutions._788;
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import org.junit.BeforeClass;
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import org.junit.Test;
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import static junit.framework.TestCase.assertEquals;
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public class _788Test {
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private static _788.Solution1 solution1;
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@BeforeClass
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public static void setup() {
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solution1 = new _788.Solution1();
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}
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@Test
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public void test1() {
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assertEquals(4, solution1.rotatedDigits(10));
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}
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}

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