将二维数组中每一列的所有元素相加 [英] Adding up all the elements of each column in a 2d array

问题描述

所以我有这个虚拟的二维数组:

So I have this dummy 2d array:

int mat[][] = {
        {10, 20, 30, 40, 50, 60, 70, 80, 90},
        {15, 25, 35, 45},
        {27, 29, 37, 48},
        {32, 33, 39, 50, 51, 89}};

我想按列累加所有值，这样它将加10 + 15 + 27 + 32并返回84，依此类推.到目前为止，我已经知道了:

I want to add up all the values by columns so it would add 10 + 15 + 27 + 32 and return 84 and so on. I have this so far:

public void sum(int[][] array) {
    int count = 0;
    for (int rows = 0; rows < array.length; rows++) {
        for (int columns = 0; columns < array[rows].length; columns++) {
            System.out.print(array[rows][columns] + "\t");
            count += array[0][0];
        }
        System.out.println();
        System.out.println("total = " + count);
    }
}

有人可以帮忙吗?同样， System.out.print(array [rows] [columns] +"\ t"); 可以按行打印出数组，有没有办法按列打印出数组?

Can anyone help with this? Also the System.out.print(array[rows][columns] + "\t" ); prints the array out by rows, is there a way to print it out by columns?

推荐答案

一种可能的解决方案是，首先找到所有子数组的最大大小，然后重复多次以查找每一列的总和，以免获得不可用的值.

One possible Solution would be to first find maximum size of all sub arrays and iterate that many times to find sum of each column avoiding unavailable values.

public static void main(String[] args) {
    int mat[][] = {{10, 20, 30, 40, 50, 60, 70, 80, 90},
            {15, 25, 35, 45},
            {27, 29, 37, 48},
            {32, 33, 39, 50, 51, 89},
    };

    // Find maximum possible length of sub array
    int maxLength = 0;
    for (int i = 0; i < mat.length; i++) {
        if (maxLength < mat[i].length)
            maxLength = mat[i].length;
    }

    for (int i = 0; i < maxLength; i++) {
        int sum = 0;
        for (int j = 0; j < mat.length; j++) {
            // Avoid if no value available for
            // ith column from this subarray
            if (i < mat[j].length)
                sum += mat[j][i];
        }
        System.out.println("Sum of Column " + i + " = " + sum);
    }
}

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