package jjn.carl.array;
import java.util.ArrayList;import java.util.Arrays;import java.util.List;
/** * @author Jiang Jining * @since 2023-06-29 22:39 */public class ToArrayDemo {    public static void main(String[] args) {        List<Integer> list = List.of(1, 2, 3, 4, 5);        int[] converted = new int[list.size()];        for (int i = 0; i < list.size(); i++) {            converted[i] = list.get(i);        }        System.out.println("Arrays.toString(array) = " + Arrays.toString(converted));                List<int[]> list2 = new ArrayList<>();        list2.add(new int[]{1, 2});        list2.add(new int[]{3, 4});        list2.add(new int[]{5, 6});        int[][] arr = list2.toArray(new int[0][]);        for (int[] part : arr) {            System.out.println("Arrays.toString(part) = " + Arrays.toString(part));        }    }}

public class LeetCode977_SortedSquares {        public int[] sortedSquares(int[] nums) {        // 双指针解法，倒序将结果放入数组        int left = 0, right = nums.length - 1;        int[] result = new int[nums.length];        int start = right;        // 结束条件, left == right        while (left <= right) {            // 按要求分别计算左边和右边的平方值            int leftSquare = nums[left] * nums[left];            int rightSquare = nums[right] * nums[right];            if (leftSquare >= rightSquare) {                result[start] = leftSquare;                left++;            } else {                result[start] = rightSquare;                right--;            }            start--;        }        return result;    }        public static void main(String[] args) {        int[] nums = new int[]{-4, -1, 0, 3, 10};        int[] result = new LeetCode977_SortedSquares().sortedSquares(nums);        System.out.println("result = " + Arrays.toString(result));    }}

package jjn.carl.array;
import java.util.Arrays;
/** * @author Jiang Jining * @since 2023-06-29 23:01 */public class LeetCode59 {        // 按题目描述的方法,不断缩小边界     public int[][] generateMatrix(int n) {        int[][] result = new int[n][n];        // left, right, top, bottom        int left = 0, right = n - 1, top = 0, bottom = n - 1, current = 1;        while (true) {            for (int i = left; i <= right; i++, current++) {                result[top][i] = current;            }            top++;            if (top > bottom) {                break;            }            for (int i = top; i <= bottom; i++, current++) {                result[i][right] = current;            }            right--;            if (right < left) {                break;            }            for (int i = right; i >= left; i--, current++) {                result[bottom][i] = current;            }            bottom--;            if (bottom < top) {                break;            }            for (int i = bottom; i >= top; i--, current++) {                result[i][left] = current;            }            left++;            if (left > right) {                break;            }        }        return result;    }        public static void main(String[] args) {        int[][] generatedMatrix = new LeetCode59().generateMatrix(3);        for (int[] matrix : generatedMatrix) {            System.out.println("Arrays.toString(generatedMatrix[i]) = " + Arrays.toString(matrix));        }    }    }