[英]Rotating a specified column 4x4 array in Java
基本上,我有一个4x4数组,其中初始化了整数0-15。 这个小任务是旋转数组的给定列,例如,如果数组为:
14 0 1 12
13 4 2 3
7 6 11 8
5 15 9 10
应用rotateColumn(3)之后,数组应如下所示:
14 0 1 10
13 4 2 12
7 6 11 3
5 15 9 8
我设法实现了行旋转方法,代码是:
public static void rotateRow(int[][] arr, int row) {
int newCurrent = arr[row][arr.length - 1];
int nextCurrent;
for (int currentIndex = 0; currentIndex < arr.length; currentIndex++) {
nextCurrent = arr[row][currentIndex];
arr[row][currentIndex] = newCurrent;
newCurrent = nextCurrent;
}
}
我为column方法尝试了类似的代码,但没有成功:
public static void rotateColumn(int[][] arr, int column) {
int newCurrent1 = arr[column][arr.length - 1];
int nextCurrent1 ;
for (int currentIndex1 = 0; currentIndex1 < arr.length; currentIndex1++){
nextCurrent1 = arr[column][currentIndex1];
arr[column][currentIndex1] = newCurrent1;
newCurrent1 = nextCurrent1;
}
}
该程序的整个代码为:
public class Puzzle {
public static final int N = 4;
public static final int NUMBER_OF_ROTATIONS = 5;
public static void main(String[] args) {
int[][] puzzle = new int[N][N];
reset(puzzle);
test(puzzle);
reset(puzzle);
scramble(puzzle);
System.out.println("### Testing puzzle game play\n");
play(puzzle);
}
public static void print(int[][] puzzle) {
for (int[] row : puzzle) {
for (int elem : row) {
System.out.printf("%4d", elem);
}
System.out.println();
}
System.out.println();
}
public static void test(int[][] puzzle) {
System.out.println("### Testing reset method\n");
print(puzzle);
System.out.println("### Testing rotate methods\n");
print(puzzle);
for (int i = 0; i < N; i++) {
System.out.println("### rotateColumn(" + i + ")\n");
rotateColumn(puzzle, i);
print(puzzle);
System.out.println("### rotateRow(" + i + ")\n");
rotateRow(puzzle, i);
print(puzzle);
}
reset(puzzle);
System.out.println("### Testing random rotations\n");
print(puzzle);
for (int i = 0; i < 5; i++){
randomRotation(puzzle);
print(puzzle);
}
}
public static void reset(int[][] puzzle) {
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++)
puzzle[i][j] = i * N + j;
}
}
public static void scramble(int[][] puzzle) {
for (int i = 0; i < NUMBER_OF_ROTATIONS; i++) {
randomRotation(puzzle);
}
}
public static void rotateRow(int[][] arr, int row) {
int newCurrent = arr[row][arr.length - 1];
int nextCurrent;
for (int currentIndex = 0; currentIndex < arr.length; currentIndex++) {
nextCurrent = arr[row][currentIndex];
arr[row][currentIndex] = newCurrent;
newCurrent = nextCurrent;
}
}
// TODO: Implement method as specified in assignment brief
public static void rotateColumn(int[][] arr, int column) {
int newCurrent1 = arr[column][arr.length - 1];
int nextCurrent1 ;
for (int currentIndex1 = 0; currentIndex1 < arr.length; currentIndex1++){
nextCurrent1 = arr[column][currentIndex1];
arr[column][currentIndex1] = newCurrent1;
newCurrent1 = nextCurrent1;
}
}
// TODO: Implement method as specified in assignment brief
public static void randomRotation(int[][] puzzle) {
}
// TODO: Implement method as specified in assignment brief
static void play(int[][] puzzle) {
}
}
有人可以指出我需要做些正确的事以确保其正常工作吗? 非常感谢您:)。
看来您在混淆行和列的内存布局。 数据数组始终是行数组。 因此,您需要更改如何处理单个元素。 您需要对原始方法进行细微调整。 以下来自rotateRow()的未经测试的代码应该有所作为。
public static void rotateColumn(int[][] arr, int col) {
int newCurrent = arr[arr.length - 1][col];
int nextCurrent;
for (int currentIndex = 0; currentIndex < arr.length; currentIndex++) {
nextCurrent = arr[currentIndex][col];
arr[currentIndex][col] = newCurrent;
newCurrent = nextCurrent;
}
}
这个怎么样?
public void rotateColumn(int[][] arr, int column) {
int[] col = new int[arr.length];
for(int row=0; row<arr.length; row++) {
col[row] = arr[row][column];
}
for(int row=0; row<arr.length; row++) {
arr[row][column] = col[(row==0) ? arr.length-1 : row-1];
}
}
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