我有一个二维字符串数组。这是一个矩阵。我需要对此矩阵进行排序,并将唯一项保存在其他矩阵的第一行中。如何仅使用自己的算法来执行此操作。我的意思是不调用方法,而是编写循环本身来对数组的元素进行排序和比较
import java.util.Scanner;
public class Coursework {
public static void main(String[] args) {
final int linesOfMatrix; //number of lines in the matrix
System.out.println("Enter number of lines: ");
Scanner sc = new Scanner(System.in);
linesOfMatrix = sc.nextInt();
Scanner sc2 = new Scanner(System.in);
String [][] matrix = new String [linesOfMatrix][]; // declare the Matrix
for(int i=0; i < matrix.length; i++) {
System.out.println("Enter a value for the string " + (i+1) + "
through a space");
matrix[i] = sc2.nextLine().split(" ");
}
sc.close();
sc2.close();
//below must be unique sort, but he dosen't work rigth
for(int i=0; i < matrix.length; i++){
for(int j=0; j < matrix[i].length-1; j++){
if(matrix[i][j].equals(matrix[i][j+1])){
matrix[i][j+1] = matrix[i][j+1];
}
}
}
System.out.println("Matrix");
for(int i=0; i < matrix.length; i++){
for(int j=0; j < matrix[i].length-1; j++){
System.out.println("[" +(i) + "][" + (j) + "]= " + matrix[i]
[j] + " [" + (i) + "][" + (j+1) + "]= " + matrix[i][j+1] );
}
}
}
}
最佳答案
使用 Map
来计数元素怎么样:
public static String[] getUnique(String[][] matrix) {
Map<String, Integer> map = new LinkedHashMap<>();
for (String[] row : matrix)
for (String col : row)
map.put(col, map.getOrDefault(col, 0) + 1);
List<String> unique = new ArrayList<>();
for (Map.Entry<String, Integer> entry : map.entrySet())
if (entry.getValue() == 1)
unique.add(entry.getKey());
return unique.toArray(new String[unique.size()]);
}
如果您不想使用Map
,那么您可以做同样的事情,但速度要慢一点:
public static String[] getUnique(String[][] matrix) {
List<String> unique = new ArrayList<>();
for (int row = 0; row < matrix.length; row++) {
for (int col = 0; col < matrix[row].length; col++) {
if (matrix[row][col] == null)
continue;
boolean foundUnique = true;
for (int i = row; i < matrix.length; i++) {
for (int j = i == row ? col : 0; j < matrix[i].length; j++) {
if (matrix[i][j] == null || (i == row && j == col))
continue;
if (matrix[i][j].equals(matrix[row][col])) {
foundUnique = false;
matrix[i][j] = null;
}
}
}
if (foundUnique)
unique.add(matrix[row][col]);
else
matrix[row][col] = null;
}
}
return unique.toArray(new String[unique.size()]);
}
或者甚至不使用List
:-):
public static String[] getUnique(String[][] matrix) {
int total = 0;
for (int row = 0; row < matrix.length; row++) {
for (int col = 0; col < matrix[row].length; col++) {
if (matrix[row][col] == null)
continue;
boolean foundUnique = true;
for (int i = row; i < matrix.length; i++) {
for (int j = i == row ? col : 0; j < matrix[i].length; j++) {
if (matrix[i][j] == null || (i == row && j == col))
continue;
if (matrix[i][j].equals(matrix[row][col])) {
foundUnique = false;
matrix[i][j] = null;
}
}
}
if (foundUnique)
total++;
else
matrix[row][col] = null;
}
}
if (total == 0)
return new String[0];
String[] res = new String[total];
for (int row = 0, i = 0; row < matrix.length; row++)
for (int col = 0; col < matrix[row].length; col++)
if (matrix[row][col] != null)
res[i++] = matrix[row][col];
return res;
}
关于java - java中如何查找二维字符串数组中的唯一元素?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47539387/