常见的数组处理算法

寻找数组中最大元素

double max = arr[0];
for (int i = 0; i < arr.length; i++) {
    if (arr[i] > max)
        max = arr[i];
}

同理寻找最小元素只需要if (arr[i] < max)

计算数组元素的平均数

double sum = 0.0;
for (int i = 0; i < arr.length; i++) {
    sum += arr[i];
}
double average = sum / arr.length;

复制数组

double[] copyArr = new double[arr.length];
for (int i = 0; i < arr.length; i++) {
    copyArr[i] = arr[i];
}

颠倒数组元素顺序

for (int i = 0; i < arr.length / 2; i++) {
    double temp = arr[i];
    arr[i] = arr[arr.length - 1 - i];
    arr[arr.length - i - 1] = temp;
}

Solution.java

public class Solution {


    public static double findMax(int[] arr) {
        double max = arr[0];
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] < max)
                max = arr[i];
        }

        return max;
    }

    public static double calAverage(int[] arr) {
        double sum = 0.0;
        for (int i = 0; i < arr.length; i++) {
            sum += arr[i];
        }
        double average = sum / arr.length;
        return average;
    }

    public static double[] copyArrary(int[] arr) {
        double[] copyArr = new double[arr.length];
        for (int i = 0; i < arr.length; i++) {
            copyArr[i] = arr[i];
        }
        return copyArr;
    }

    public static double[] reverseOrder(double[] arr) {
        for (int i = 0; i < arr.length / 2; i++) {
            double temp = arr[i];
            arr[i] = arr[arr.length - 1 - i];
            arr[arr.length - i - 1] = temp;
        }
        return arr;
    }

    public static void main(String[] args) {

        int arr[] = {1, 2, 3, 4};
        double arr2[] = {1, 2, 3, 4};
        double x = findMax(arr);
        System.out.println(x);
        System.out.println(calAverage(arr));
        double[] a = copyArrary(arr);
        for (double n : a)
            System.out.print(n + " ");

        System.out.println();
        double[] b = reverseOrder(arr2);
        for (double n : arr2)
            System.out.print(n + " ");
    }
}