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二叉树遍历、深度、直径

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Lines changed: 31 additions & 0 deletions

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	`1`	`+/*`
	`2`	`+ * @lc app=leetcode.cn id=104 lang=java`
	`3`	`+ *`
	`4`	`+ * [104] 二叉树的最大深度`
	`5`	`+ */`
	`6`	`+`
	`7`	`+// @lc code=start`
	`8`	`+/**`
	`9`	`+ * Definition for a binary tree node.`
	`10`	`+ * public class TreeNode {`
	`11`	`+ * int val;`
	`12`	`+ * TreeNode left;`
	`13`	`+ * TreeNode right;`
	`14`	`+ * TreeNode() {}`
	`15`	`+ * TreeNode(int val) { this.val = val; }`
	`16`	`+ * TreeNode(int val, TreeNode left, TreeNode right) {`
	`17`	`+ * this.val = val;`
	`18`	`+ * this.left = left;`
	`19`	`+ * this.right = right;`
	`20`	`+ * }`
	`21`	`+ * }`
	`22`	`+ */`
	`23`	`+classSolution {`
	`24`	`+publicintmaxDepth(TreeNoderoot) {`
	`25`	`+if (root ==null) {`
	`26`	`+return0;`
	`27`	`+ }`
	`28`	`+return1 +Math.max(maxDepth(root.left),maxDepth(root.right));`
	`29`	`+ }`
	`30`	`+}`
	`31`	`+// @lc code=end`

Lines changed: 39 additions & 0 deletions

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	`1`	`+importjava.util.ArrayList;`
	`2`	`+importjava.util.List;`
	`3`	`+`
	`4`	`+/*`
	`5`	`+ * @lc app=leetcode.cn id=144 lang=java`
	`6`	`+ *`
	`7`	`+ * [144] 二叉树的前序遍历`
	`8`	`+ */`
	`9`	`+`
	`10`	`+// @lc code=start`
	`11`	`+/**`
	`12`	`+ * Definition for a binary tree node.`
	`13`	`+ * public class TreeNode {`
	`14`	`+ * int val;`
	`15`	`+ * TreeNode left;`
	`16`	`+ * TreeNode right;`
	`17`	`+ * TreeNode() {}`
	`18`	`+ * TreeNode(int val) { this.val = val; }`
	`19`	`+ * TreeNode(int val, TreeNode left, TreeNode right) {`
	`20`	`+ * this.val = val;`
	`21`	`+ * this.left = left;`
	`22`	`+ * this.right = right;`
	`23`	`+ * }`
	`24`	`+ * }`
	`25`	`+ */`
	`26`	`+classSolution {`
	`27`	`+publicList<Integer>preorderTraversal(TreeNoderoot) {`
	`28`	`+List<Integer>list =newArrayList<Integer>();`
	`29`	`+if (root ==null) {`
	`30`	`+returnlist;`
	`31`	`+ }`
	`32`	`+`
	`33`	`+list.add(root.val);`
	`34`	`+list.addAll(preorderTraversal(root.left));`
	`35`	`+list.addAll(preorderTraversal(root.right));`
	`36`	`+returnlist;`
	`37`	`+ }`
	`38`	`+}`
	`39`	`+// @lc code=end`

Lines changed: 35 additions & 0 deletions

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	`1`	`+/*`
	`2`	`+ * @lc app=leetcode.cn id=226 lang=java`
	`3`	`+ *`
	`4`	`+ * [226] 翻转二叉树`
	`5`	`+ */`
	`6`	`+`
	`7`	`+// @lc code=start`
	`8`	`+/**`
	`9`	`+ * Definition for a binary tree node.`
	`10`	`+ * public class TreeNode {`
	`11`	`+ * int val;`
	`12`	`+ * TreeNode left;`
	`13`	`+ * TreeNode right;`
	`14`	`+ * TreeNode() {}`
	`15`	`+ * TreeNode(int val) { this.val = val; }`
	`16`	`+ * TreeNode(int val, TreeNode left, TreeNode right) {`
	`17`	`+ * this.val = val;`
	`18`	`+ * this.left = left;`
	`19`	`+ * this.right = right;`
	`20`	`+ * }`
	`21`	`+ * }`
	`22`	`+ */`
	`23`	`+classSolution {`
	`24`	`+publicTreeNodeinvertTree(TreeNoderoot) {`
	`25`	`+if (root ==null)`
	`26`	`+returnnull;`
	`27`	`+TreeNodetmp =root.left;`
	`28`	`+root.left =root.right;`
	`29`	`+root.right =tmp;`
	`30`	`+invertTree(root.left);`
	`31`	`+invertTree(root.right);`
	`32`	`+returnroot;`
	`33`	`+ }`
	`34`	`+}`
	`35`	`+// @lc code=end`

Lines changed: 44 additions & 0 deletions

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	`1`	`+/*`
	`2`	`+ * @lc app=leetcode.cn id=543 lang=java`
	`3`	`+ *`
	`4`	`+ * [543] 二叉树的直径`
	`5`	`+ */`
	`6`	`+`
	`7`	`+// @lc code=start`
	`8`	`+/**`
	`9`	`+ * Definition for a binary tree node.`
	`10`	`+ * public class TreeNode {`
	`11`	`+ * int val;`
	`12`	`+ * TreeNode left;`
	`13`	`+ * TreeNode right;`
	`14`	`+ * TreeNode() {}`
	`15`	`+ * TreeNode(int val) { this.val = val; }`
	`16`	`+ * TreeNode(int val, TreeNode left, TreeNode right) {`
	`17`	`+ * this.val = val;`
	`18`	`+ * this.left = left;`
	`19`	`+ * this.right = right;`
	`20`	`+ * }`
	`21`	`+ * }`
	`22`	`+ */`
	`23`	`+classSolution {`
	`24`	`+privateintmaxDiameter =0;`
	`25`	`+`
	`26`	`+publicintdiameterOfBinaryTree(TreeNoderoot) {`
	`27`	`+traverse(root);`
	`28`	`+returnmaxDiameter;`
	`29`	`+ }`
	`30`	`+`
	`31`	`+privateinttraverse(TreeNoderoot) {`
	`32`	`+if (root ==null) {`
	`33`	`+return0;`
	`34`	`+ }`
	`35`	`+// 计算左右子树高度`
	`36`	`+intleft =traverse(root.left);`
	`37`	`+intright =traverse(root.right);`
	`38`	`+// 更新最大直径`
	`39`	`+maxDiameter =Math.max(left +right,maxDiameter);`
	`40`	`+`
	`41`	`+return1 +Math.max(left,right);`
	`42`	`+ }`
	`43`	`+}`
	`44`	`+// @lc code=end`

Lines changed: 18 additions & 0 deletions

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	`1`	`+publicclassTreeNode {`
	`2`	`+intval;`
	`3`	`+TreeNodeleft;`
	`4`	`+TreeNoderight;`
	`5`	`+`
	`6`	`+TreeNode() {`
	`7`	`+ }`
	`8`	`+`
	`9`	`+TreeNode(intval) {`
	`10`	`+this.val =val;`
	`11`	`+ }`
	`12`	`+`
	`13`	`+TreeNode(intval,TreeNodeleft,TreeNoderight) {`
	`14`	`+this.val =val;`
	`15`	`+this.left =left;`
	`16`	`+this.right =right;`
	`17`	`+ }`
	`18`	`+}`

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