Java列表中的最小值和最大值

给定一个未排序的整数列表，找出其中的最大值和最小值。

Input : list = [10, 4, 3, 2, 1, 20]
Output : max = 20, min = 1

Input : list = [10, 400, 3, 2, 1, -1]
Output : max = 400, min = -1

排序

这是效率最低的方法，但可以完成工作。这个想法是按自然顺序对列表进行排序，然后第一个或最后一个元素将分别是最小和最大元素。下面是Java中的实现。

// This java program find minimum and maximum value
// of an unsorted list of Integer by using Collection
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
  
public class GFG {
  
    // function to find minimum value in an unsorted
    // list in Java using Collection
    public static Integer findMin(List list)
    {
  
        // check list is empty or not
        if (list == null || list.size() == 0) {
            return Integer.MAX_VALUE;
        }
  
        // create a new list to avoid modification 
        // in the original list
        List sortedlist = new ArrayList<>(list);
  
        // sort list in natural order
        Collections.sort(sortedlist);
  
        // first element in the sorted list
        // would be minimum
        return sortedlist.get(0);
    }
  
    // function return maximum value in an unsorted
    // list in Java using Collection
    public static Integer findMax(List list)
    {
  
        // check list is empty or not
        if (list == null || list.size() == 0) {
            return Integer.MIN_VALUE;
        }
  
        // create a new list to avoid modification
        // in the original list
        List sortedlist = new ArrayList<>(list);
  
        // sort list in natural order
        Collections.sort(sortedlist);
  
        // last element in the sorted list would be maximum
        return sortedlist.get(sortedlist.size() - 1);
    }
  
    public static void main(String[] args)
    {
  
        // create an ArrayList Object list
        List list = new ArrayList<>();
  
        // add element in ArrayList object list
        list.add(44);
        list.add(11);
        list.add(22);
        list.add(33);
  
        // print min amd max value of ArrayList
        System.out.println("Min: " + findMin(list));
        System.out.println("Max: " + findMax(list));
    }
}

输出：

Min: 11
Max: 44

集合.max()

Collections.min() 方法返回指定集合中的最小元素，Collections.max() 根据其元素的自然顺序返回指定集合中的最大元素。

// This java program find minimum and maximum value
// of an unsorted list of Integer by using Collection
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
  
public class GFG {
  
    // function to find minimum value in an unsorted
    // list in Java using Collection
    public static Integer findMin(List list)
    {
  
        // check list is empty or not
        if (list == null || list.size() == 0) {
            return Integer.MAX_VALUE;
        }
  
        // return minimum value of the ArrayList
        return Collections.min(list);
    }
  
    // function return maximum value in an unsorted
    //  list in Java using Collection
    public static Integer findMax(List list)
    {
  
        // check list is empty or not
        if (list == null || list.size() == 0) {
            return Integer.MIN_VALUE;
        }
  
        // return maximum value of the ArrayList
        return Collections.max(list);
    }
  
    public static void main(String[] args)
    {
  
        // create an ArrayList Object list
        List list = new ArrayList<>();
  
        // add element in ArrayList object list
        list.add(44);
        list.add(11);
        list.add(22);
        list.add(33);
  
        // print min amd max value of ArrayList
        System.out.println("Min: " + findMin(list));
        System.out.println("Max: " + findMax(list));
    }
}

输出：

Min: 11
Max: 44

幼稚的

这是在未排序列表中查找最小值和最大值的天真方法，我们检查列表中存在的所有值并保持迄今为止找到的最小值和最大值。

// This java program find minimum and maximum value
// of an unsorted list of Integer
import java.util.ArrayList;
import java.util.List;
  
public class GFG {
  
    // Naive function to find minimum value in an
    // unsorted list in Java
    public static Integer findMin(List list)
    {
        // initialize min to some maximum value
        Integer min = Integer.MAX_VALUE;
  
        // loop through every element in the list and
        // compare min found so far with current value
        for (Integer i : list) {
  
            // update min if found to be more than 
            // the current element
            if (min > i) {
                min = i;
            }
        }
  
        return min;
    }
  
    // This function return maximum value in an
    // unsorted list in Java
    public static Integer findMax(List list)
    {
        // initialize max variable to minimum value
        Integer max = Integer.MIN_VALUE;
  
        // loop for compare to current max value
        // with all list element and find maximum value
        for (Integer i : list) {
  
            // update max if found to be less than 
            // the current element
            if (max < i) {
                max = i;
            }
        }
  
        return max;
    }
  
    public static void main(String[] args)
    {
        // create an ArrayList Object list
        List list = new ArrayList<>();
        // add element in ArrayList object list
        list.add(44);
        list.add(11);
        list.add(22);
        list.add(33);
  
        // print min amd max value of ArrayList
        System.out.println("Min: " + findMin(list));
        System.out.println("Max: " + findMax(list));
    }
}

输出：

Min: 11
Max: 44