使用掃描儀將元素插入二維數組時出現邏輯錯誤

Question

我正在嘗試對矩陣行求和當我只是將元素放入二維數組 output 是正確的但是當我嘗試使用掃描儀 output 結果是不同的

樣本輸入

2
1 2 
3 4

Output：

3
7

下面的代碼結果正確

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

public class matrix {
    public static void main(String[] args) throws IOException {
       Scanner sc = new Scanner(System.in);

 int a[][] = {       
                        {1, 2,},    
                           
                        { 3, 4}    
                    };    

int rows, cols, sumRow, sumCol;    
            
        //Initialize matrix a  
              
          //Calculates number of rows and columns present in given matrix    
          rows = a.length;    
        cols = a[0].length;    
            
        //Calculates sum of each row of given matrix    
        for(int i = 0; i < rows; i++){    
            sumRow = 0;    
            for(int j = 0; j < cols; j++){    
              sumRow = sumRow + a[i][j];    
            }    
            System.out.println(sumRow);    
        }    
            
        //Calculates sum of each column of given matrix    
        for(int i = 0; i < cols; i++){    
            sumCol = 0;    
            for(int j = 0; j < rows; j++){    
              sumCol = sumCol + a[j][i];    
            }
        }
    }
}

如果我嘗試使用掃描儀，結果不正確

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

public class matrix {
    public static void main(String[] args) throws IOException {
       Scanner sc = new Scanner(System.in);

int row = sc.nextInt();

int column = sc.nextInt();

int [][] a = new int[row][column];
for (int i = 0; i < row; i++)
{
    for(int j = 0; j < column; j++) {
       
    a[i][j] = sc.nextInt(); 
    }
}

int rows, cols, sumRow, sumCol;    
            
        //Initialize matrix a  
              
          //Calculates number of rows and columns present in given matrix    
          rows = a.length;    
        cols = a[0].length;    
            
        //Calculates sum of each row of given matrix    
        for(int i = 0; i < rows; i++){    
            sumRow = 0;    
            for(int j = 0; j < cols; j++){    
              sumRow = sumRow + a[i][j];    
            }    
            System.out.println(sumRow);    
        }    
            
        //Calculates sum of each column of given matrix    
        for(int i = 0; i < cols; i++){    
            sumCol = 0;    
            for(int j = 0; j < rows; j++){    
              sumCol = sumCol + a[j][i];    
            }           
        }
    }
} 

Answer 1

使用您提供的示例輸入，您不應該讀取行數和列數，而只是讀取行數和列數的單個 int：

int size = sc.nextInt();

int [][] a = new int[size][size];
for (int i = 0; i < size; i++) {
    for(int j = 0; j < size; j++) {       
        a[i][j] = sc.nextInt(); 
    }
}

Answer 2

我認為您的代碼沒有任何邏輯問題。 但是，保持代碼整潔和用戶友好同樣重要。 如果您對編程很認真，我建議您解決以下幾點：

1. 以下聲明是不必要的：

    rows = a.length; cols = a[0].length;

   您可以簡單地使用row和column ，而不是為同一事物創建rows和cols 。

   您應該刪除所有在您的代碼中產生噪音的不必要的東西。

2. 您錯過了打印每列的總和，即

   System.out.println(sumCol);

3. 對於此代碼，您不需要使用main聲明throws IOException 。

4. 您應該始終顯示描述輸入的消息； 否則，用戶對他/她應該輸入什么一無所知。

   下面給出了包含這些注釋的代碼：

    import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.print("Enter the number of rows: "); int row = sc.nextInt(); System.out.print("Enter the number of columns: "); int column = sc.nextInt(); int[][] a = new int[row][column]; for (int i = 0; i < row; i++) { System.out.println("Enter " + column + " integers: "); for (int j = 0; j < column; j++) { a[i][j] = sc.nextInt(); } } int sumRow, sumCol; // Calculates sum of each row of given matrix for (int i = 0; i < row; i++) { sumRow = 0; for (int j = 0; j < column; j++) { sumRow = sumRow + a[i][j]; } System.out.println("Sum of row " + i + ": " + sumRow); } // Calculates sum of each column of given matrix for (int i = 0; i < column; i++) { sumCol = 0; for (int j = 0; j < row; j++) { sumCol = sumCol + a[j][i]; } System.out.println("Sum of column " + i + ": " + sumCol); } } }

   示例運行：

    Enter the number of rows: 3 Enter the number of columns: 4 Enter 4 integers: 1 9 2 8 Enter 4 integers: 2 8 3 7 Enter 4 integers: 3 7 4 6 Sum of row 0: 20 Sum of row 1: 20 Sum of row 2: 20 Sum of column 0: 6 Sum of column 1: 24 Sum of column 2: 9 Sum of column 3: 21