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| 1 | +package leetcode2018; |
| 2 | + |
| 3 | +import java.util.ArrayList; |
| 4 | +import java.util.List; |
| 5 | + |
| 6 | +public class Trees { |
| 7 | + |
| 8 | + public static void main(String[] args){ |
| 9 | + Trees test = new Trees(); |
| 10 | + TreeNode t = new TreeNode(5); |
| 11 | + t.left = new TreeNode(3); |
| 12 | + t.left.left = new TreeNode(2); |
| 13 | + t.left.right = new TreeNode(4); |
| 14 | + t.right = new TreeNode(7); |
| 15 | + //t.right.left = new TreeNode(6); |
| 16 | + //t.right.right= new TreeNode(8); |
| 17 | + test.inOrderTraversal(t); |
| 18 | + System.out.println(); |
| 19 | + test.preOrderTraversal(t); |
| 20 | + System.out.println(); |
| 21 | + test.postOrderTraversal(t); |
| 22 | + //System.out.println(test.minDepth(t)); |
| 23 | + //test.binaryTreePaths(t); |
| 24 | + //test.lowestCommonAncestor(t, t.left.left, t.left.right); |
| 25 | + } |
| 26 | + |
| 27 | + public int minDepth(TreeNode root) { |
| 28 | + if(root==null) return 0; |
| 29 | + int l = minDepth(root.left); |
| 30 | + int r = minDepth(root.right); |
| 31 | + System.out.println("l"+l+ " :"+r); |
| 32 | + if(r==0) return l+1; |
| 33 | + if(l==0) return r+1; System.out.println("AAl"+l+ " :"+r); |
| 34 | + int re= Math.min(l, r)+1; System.out.println(re); |
| 35 | + return re; |
| 36 | + |
| 37 | + } |
| 38 | + |
| 39 | + public int maxDepth(TreeNode root) { |
| 40 | + if(root == null) return 0; |
| 41 | + int l = maxDepth(root.left)+1; |
| 42 | + int r= maxDepth(root.right)+1; |
| 43 | + return Math.max(l,r); |
| 44 | + } |
| 45 | + |
| 46 | + public void inOrderTraversal(TreeNode t){ |
| 47 | + if(t!=null){ |
| 48 | + inOrderTraversal(t.left); |
| 49 | + System.out.print(t.val); |
| 50 | + inOrderTraversal(t.right); |
| 51 | + } |
| 52 | + } |
| 53 | + |
| 54 | + public List<String> binaryTreePaths(TreeNode root) { |
| 55 | + List<String> list = new ArrayList<>(); |
| 56 | + if(root==null) return list; |
| 57 | + dfs(root,list, ""); |
| 58 | + return list; |
| 59 | + } |
| 60 | + public void dfs(TreeNode root, List<String> list, String path){ |
| 61 | + if(root.left==null && root.right == null){ |
| 62 | + list.add(path+ root.val); |
| 63 | + return; |
| 64 | + } |
| 65 | + path = path+ root.val +"->"; |
| 66 | + if(root.left!=null) dfs(root.left, list, path); |
| 67 | + if(root.right!=null) dfs(root.right, list, path); |
| 68 | + } |
| 69 | + |
| 70 | + public void preOrderTraversal(TreeNode t){ |
| 71 | + if(t!=null){ |
| 72 | + System.out.print(t.val); |
| 73 | + preOrderTraversal(t.left); |
| 74 | + preOrderTraversal(t.right); |
| 75 | + } |
| 76 | + } |
| 77 | + |
| 78 | + public void postOrderTraversal(TreeNode t){ |
| 79 | + if(t!=null){ |
| 80 | + postOrderTraversal(t.left); |
| 81 | + postOrderTraversal(t.right); |
| 82 | + System.out.print(t.val); |
| 83 | + } |
| 84 | + } |
| 85 | + |
| 86 | + public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) { |
| 87 | + if(root==null || root==p || q== root) return root; System.out.println(root.val); |
| 88 | + TreeNode left = lowestCommonAncestor(root.left, p, q); |
| 89 | + TreeNode right = lowestCommonAncestor(root.right, p, q); |
| 90 | + if(left!= null && right!=null) { System.out.println("mid:"+root.val); return root;}; |
| 91 | + System.out.println("left" +left+ " right:"+right); |
| 92 | + TreeNode re = left!=null? left: right; |
| 93 | + return re; |
| 94 | + } |
| 95 | + |
| 96 | +} |
| 97 | + |
| 98 | +class TreeNode{ |
| 99 | + int val; |
| 100 | + TreeNode left; |
| 101 | + TreeNode right; |
| 102 | + TreeNode(int x){ |
| 103 | + val=x; |
| 104 | + } |
| 105 | +} |
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