Java 如何在二维数组中每隔一列交替元素的顺序

空2D数组

a

应填充以下值：

1 8 9 16 17
2 7 10 15 18
3 6 11 14 19
4 5 12 13 20

我一直很难弄清楚如何颠倒列的顺序。这是我得到的最接近的结果：

int [][] a = new int[4][5];
        int count = 1;
        for(int c = 0; c < a[0].length; c++) {
            for(int r = 0; r < a.length; r++) {
                a[r][c] = count;
                count++;
            if(r% 2 == 0 && c % 2 != 0) {
                count = 20;
                a[r][c] = 20;
                count--;
           }    
       }
}

int[]a=新的int[4][5]；
整数计数=1；
for（int c=0；c

您应该定义一个变量，该变量定义每次迭代时要移动的方向，我将其命名为

符号

。若符号为正，则该列将向下填充，否则将向相反方向移动

int [][] a = new int[4][5];
int count = 1;
int sign = 1;
for(int j = 0 ; j < 5 ; j++){
    if(sign==1)
        for(int i = 0 ; i < 4 ; i++){
            a[i][j]=count;
            count++;
        }
    else
        for(int i = 3 ; i >=0 ; i--){
            a[i][j]=count;
            count++;
        }
    sign *= -1;
}

---

您应该定义一个变量，该变量定义了在每次迭代中要移动的方向，我将其命名为

sign

。若符号为正，则该列将向下填充，否则将向相反方向移动

int [][] a = new int[4][5];
int count = 1;
int sign = 1;
for(int j = 0 ; j < 5 ; j++){
    if(sign==1)
        for(int i = 0 ; i < 4 ; i++){
            a[i][j]=count;
            count++;
        }
    else
        for(int i = 3 ; i >=0 ; i--){
            a[i][j]=count;
            count++;
        }
    sign *= -1;
}

---

您所处的轨道是正确的，插入偶数列时只需将行反转即可

 public static void main(String []args){  

    int count =1;
    int columnCount =5;
    int rowCount = 4;

    int [][] a = new int[rowCount][columnCount];


    for (int column = 0; column<columnCount; column ++ ) {
        for (int row = 0; row <rowCount; row ++) { 

          if(column%2==0){
              a[row][column] = count; 
          }else {
              a[rowCount-row-1][column] =count;
          }
          count ++ ;
        }     
    }   

    //validate results 
    for (int row = 0; row <rowCount; row ++) { 
        for (int column = 0; column<columnCount; column ++ ) { 
            System.out.print (a[row][column] +" ");
        }
        System.out.println();
    }

 }

---

您所处的轨道是正确的，插入偶数列时只需将行反转即可

 public static void main(String []args){  

    int count =1;
    int columnCount =5;
    int rowCount = 4;

    int [][] a = new int[rowCount][columnCount];


    for (int column = 0; column<columnCount; column ++ ) {
        for (int row = 0; row <rowCount; row ++) { 

          if(column%2==0){
              a[row][column] = count; 
          }else {
              a[rowCount-row-1][column] =count;
          }
          count ++ ;
        }     
    }   

    //validate results 
    for (int row = 0; row <rowCount; row ++) { 
        for (int column = 0; column<columnCount; column ++ ) { 
            System.out.print (a[row][column] +" ");
        }
        System.out.println();
    }

 }

$java -Xmx128M -Xms16M HelloWorld
1 8 9 16 17 
2 7 10 15 18 
3 6 11 14 19 
4 5 12 13 20