矩阵对角线和
题目:求一个3*3矩阵对角线元素之和(升级版:可以打印任何一个n*n矩阵的对角线的和)
public class Arithmetic_matrixSum { public static void main(String[] args) { int[][] arr = new int[3][3]; setMatrix(arr); printMatrix(arr); getMatrixDiagonalSum(arr); } /**设置随机矩阵*/ public static void setMatrix(int[][] arr){ Random random = new Random(); int num = 0; for (int i = 0; i < arr.length; i++) { //行 for (int j = 0; j < arr[i].length; j++) { //列 num = random.nextInt(100); arr[i][j] = num; } } } /**打印矩阵*/ public static void printMatrix(int[][] arr){ for (int i = 0; i < arr.length; i++) { //行 for (int j = 0; j < arr[i].length; j++) { //列 System.out.print(arr[i][j]+"\t"); } System.out.println(""); } } /**求矩阵对角线和*/ public static void getMatrixDiagonalSum(int[][] arr){ int sum = 0; if (arr==null||(arr.length!=arr[0].length)) { //不是正方形矩阵 System.out.println("该矩阵无对角线,请输入n*n矩阵"); return; } System.out.println("求对角线:"); for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr[i].length; j++) { if (i==j) { //当行等于列时 sum += arr[i][j]; System.out.print(arr[i][j]+"\t"); } } } System.out.println("一条对角线和"+sum); sum = 0; for (int i = 0; i < arr.length; i++) { for (int j = 0; j < arr[i].length; j++) { if (i+j==arr.length-1) { //另一条对角线规律 sum += arr[i][j]; System.out.print(arr[i][j]+"\t"); } } } System.out.println("另一条对角线和"+sum); } }
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