Leetcode刷题 - ACM模式模板

1. 【输入输出】普通数组

public static void main(String[] args) {
    	//输入
        Scanner scanner = new Scanner(System.in);
        String[] numsStr = scanner.nextLine().split(" ");

        int[] nums = new int[numsStr.length];
        for(int i=0;i<nums.length;i++){
            nums[i] = Integer.parseInt(numsStr[i]);
        }
        int target = scanner.nextInt();
		
    	//解题
        int[] result = solution(nums, target);
		
    	//输出
        System.out.println(Arrays.toString(result));
    }

2. 【输入输出+链表定义】链表

package hot100.listnode;

import java.util.*;

public class AddTwoNumbers {
    
    static class ListNode{
        int val;
        hot100.listnode.ListNode next;
        public ListNode(){}
        public ListNode(int val){
            this.val = val;
            next = null;
        }
    }
    
    public static ListNode solution(ListNode l1, ListNode l2) {
        ...
    }

    private static ListNode arrayToListNode(int[] arr) {
        ListNode dummy = new ListNode(-1);
        ListNode cur = dummy;
        for (int i = 0; i < arr.length; i++) {
            cur.next = new ListNode(arr[i]);
            cur = cur.next;
            if (i == arr.length - 1) {
                cur.next = null;
            }
        }
        return dummy.next;
    }

    public static void main(String[] args) {
        // 输入
        Scanner scanner = new Scanner(System.in);
        String[] numsStr1 = scanner.nextLine().split(",");
        int[] nums1 = new int[numsStr1.length];
        for (int i = 0; i < numsStr1.length; i++) {
            nums1[i] = Integer.parseInt(numsStr1[i]);
        }
        String[] numsStr2 = scanner.nextLine().split(",");
        int[] nums2 = new int[numsStr2.length];
        for (int i = 0; i < numsStr2.length; i++) {
            nums2[i] = Integer.parseInt(numsStr2[i]);
        }

        ListNode list1 = arrayToListNode(nums1);
        ListNode list2 = arrayToListNode(nums2);
		
        //解题
        ListNode result = addTwoNumbers(list1, list2);

        //输出
        while(result!=null){
            System.out.print(result.val);
            if(result.next!=null){
                System.out.print("->");
            }
            result = result.next;
        }
    }
}

3. 【输入输出+二叉树定义】二叉树

package hot100.BinaryTree;

import java.util.*;

public class InorderTraversal {
    static class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }

    private static TreeNode buildTree(String[] arr) {
        if (arr.length == 0 || arr[0].equals("null")) {
            return null;
        }

        Queue<TreeNode> que = new LinkedList<>();
        TreeNode root = new TreeNode(Integer.parseInt(arr[0]));
        que.offer(root);

        int index = 1;
        while (!que.isEmpty() && index < arr.length) {
            TreeNode currentNode = que.poll();
            if (!arr[index].equals("null")) {
                currentNode.left = new TreeNode(Integer.parseInt(arr[index]));
                que.offer(currentNode.left);
            }
            index++;

            if (index < arr.length && !arr[index].equals("null")) {
                currentNode.right = new TreeNode(Integer.parseInt(arr[index]));
                que.offer(currentNode.right);
            }
            index++;

        }

        return root;
    }

    public static void inorderTraversal(TreeNode node) {
        if (node == null) {
            return;
        }
        inorderTraversal(node.left);
        System.out.println(node.val);
        inorderTraversal(node.right);
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String[] numStr = scanner.nextLine().split(",");
        TreeNode root = buildTree(numStr);

        inorderTraversal(root);
    }
}