8000 add 965 · sakurazz/Leetcode-1@0655eda · 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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|965|[Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_965.java) | O(n) | O(h) | |Easy| DFS, recursion
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|961|[N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_961.java) | O(n) | O(1) | |Easy|
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|944|[Delete Columns to Make Sorted](https://leetcode.com/problems/delete-columns-to-make-sorted/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_944.java) | O(n) | O(1) | |Easy|
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|941|[Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_941.java) | O(n) | O(1) | |Easy|

‎src/main/java/com/fishercoder/solutions/_965.java

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package com.fishercoder.solutions;
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import com.fishercoder.common.classes.TreeNode;
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/**
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* 965. Univalued Binary Tree
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*
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* A binary tree is univalued if every node in the tree has the same value.
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*
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* Return true if and only if the given tree is univalued.
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*
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* Example 1:
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*
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* 1
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* / \
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* 1 1
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* / \ \
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* 1 1 1
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*
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* Input: [1,1,1,1,1,null,1]
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* Output: true
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*
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*
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* Example 2:
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* 2
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* / \
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* 2 2
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* / \
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* 5 2
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*
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* Input: [2,2,2,5,2]
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* Output: false
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*
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*
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* Note:
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*
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* The number of nodes in the given tree will be in the range [1, 100].
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* Each node's value will be an integer in the range [0, 99].
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*/
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public class _965 {
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public static class Solution1 {
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public boolean isUnivalTree(TreeNode root) {
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if (root == null) {
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return true;
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}
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return dfs(root, root.val);
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}
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private boolean dfs(TreeNode root, int value) {
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if (root == null) {
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return true;
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}
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if (root.val != value) {
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return false;
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}
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return dfs(root.left, value) && dfs(root.right, value);
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}
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}
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}

‎src/test/java/com/fishercoder/_965Test.java

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package com.fishercoder;
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import com.fishercoder.common.classes.TreeNode;
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import com.fishercoder.common.utils.TreeUtils;
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import com.fishercoder.solutions._14;
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import com.fishercoder.solutions._965;
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import java.util.Arrays;
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import java.util.List;
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import org.junit.BeforeClass;
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import org.junit.Test;
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import static org.junit.Assert.assertEquals;
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public class _965Test {
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private static _965.Solution1 solution1;
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private static TreeNode root;
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@BeforeClass
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public static void setup() {
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solution1 = new _965.Solution1();
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}
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@Test
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public void test1() {
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root = TreeUtils.constructBinaryTree(Arrays.asList(1, 1, 1, 1, 1, null, 1));
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assertEquals(true, solution1.isUnivalTree(root));
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}
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@Test
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public void test2() {
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root = TreeUtils.constructBinaryTree(Arrays.asList(2, 2, 2, 5, 2));
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assertEquals(false, solution1.isUnivalTree(root));
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}
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}

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