Question

I am trying to use jagged array to determine if the matrix is upper or lower triangle.

here is what I have.

The problem is the method returns true for both upper and lower triangular.

import java.util.*;
import java.lang.*;
import java.io.*;

public class Main {
    public static boolean isUpper(int[][] array){
        for (int i = 0; i < array.length; i++) {
            for (int j = 0; j < array[i].length; j++) {
             if(array.length == array[i].length){
                   return true;
               }
            }
        }
        System.out.println("false");
        return false;
    }
  public static void main(String args[]) {
    int myA[][] = {{3,4,5},{6,7},{8}};
    int myB[][] = {{8},{6,7},{5,4,3}};
    isUpper(myB);
  }
}

Answer 1

Checking the length with the first row should return true for myA and false for myB

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
public class Jagged {
    public static boolean isUpper(int[][] array){
        for (int i = 0; i < array.length; i++) {
            if(array.length == array[0].length){
                System.out.println("yes");
                return true;
            }
        }
        System.out.println("no");
        return false;
    }
  public static void main(String args[]) {
    int myA[][] = {{3,4,5},{6,7},{8}};
    int myB[][] = {{8},{6,7},{5,4,3}};
    isUpper(myA);
  }

 }

Answer 2

The code returns true when the `length` of any inner Array is the same as the `length` for the containing array. Both arrays (`myA` and `myB`) have a length of `3`, so that means that if any of the inner arrays have a length of `3` it will `return true`. `myA` and `myB` both have an inner array with a length of 3 (`{3,4,5}` for `myA` and `{5,4,3}` for `myB`)so both will return `true`.

Using jagged array to determine upper or lower triangular

2 个答案: