Java 中的 Java.util.TreeMap .钻洞入口()和钻洞键()
哎哎哎:# t0]https://www . geeksforgeeks . org/Java-util-tree map-flood-Java/
在许多地方，找到小于给定值的最大值是很有用的，在基于地图的容器中拥有这个特征总是一个好处。Java.util.TreeMap 也使用 floor()函数提供了这个功能。有两种变体，下面将讨论这两种变体。
1。floorEntry() : 它返回与小于或等于给定键的最大键相关联的键值映射，如果没有这样的键，则返回 null。
Parameters:
key : This is the key to be matched.
Return Value:
It returns an entry with the greatest key less than or equal to key,
or null if there is no such key.
Exception:
ClassCastException : This exception is thrown if the specified
key cannot be compared with the keys currently in the map.
NullPointerException : This exception is thrown if the specified
key is null and this map uses natural ordering, or its comparator does not permit null keys.
// Java code to demonstrate the working
// of floorEntry()
import java.io.*;
import java.util.*;
public class floorEntry {
public static void main(String[] args)
{
// Declaring the tree map of Integer and String
TreeMap<Integer, String> tmp = new TreeMap<Integer, String>();
// assigning the values in the tree map
// using put()
tmp.put(10, "ten");
tmp.put(7, "seven");
tmp.put(19, "nineteen");
tmp.put(3, "three");
// use of floorEntry()
// displays the floor value of 6
// prints 3=three
System.out.println("The greatest key-value less than 6 is : "
+ tmp.floorEntry(6));
}
}
输出:
The greatest key-value less than 6 is : 3=three
2。floorKey() : 返回小于或等于给定键的最大键，如果没有该键，则返回 null。
Parameters:
key : This is the key to be matched.
Return Value:
It returns an entry with the greatest key less than or equal to key, or
null if there is no such key.
Exception:
ClassCastException : This exception is thrown if the specified
key cannot be compared with the keys currently in the map.
NullPointerException : This exception is thrown if the specified key
is null and this map uses natural ordering, or its comparator does not permit null keys.
// Java code to demonstrate the working
// of floorKey()
import java.io.*;
import java.util.*;
public class floorKey {
public static void main(String[] args)
{
// Declaring the tree map of Integer and String
TreeMap<Integer, String> tmp = new TreeMap<Integer, String>();
// assigning the values in the tree map
// using put()
tmp.put(10, "ten");
tmp.put(7, "seven");
tmp.put(19, "nineteen");
tmp.put(3, "three");
// use of floorKey()
// displays the floor key of
// prints 3
System.out.println("The greatest key less than 6 is : "
+ tmp.floorKey(6));
}
}
输出:
The greatest key less than 6 is : 3
实际应用:该函数的可能应用是丰富的。从给定汽油或给定配料的可能菜肴的最大距离开始。前一个在下面的代码中讨论。
// Java code to demonstrate the application
// of floorKey() and floorEntry
import java.io.*;
import java.util.*;
public class floorappli {
public static void main(String[] args)
{
// Declaring the tree map of Integer and String
TreeMap<Integer, String> destin = new TreeMap<Integer, String>();
// assigning the km with destination
// from beginning
// using put()
destin.put(10, "Delhi");
destin.put(7, "Gurgaon");
destin.put(19, "Noida");
destin.put(3, "Ring Road");
// Entering the available Petrol (consider 1km/litre)
int petr = 12;
// Maximum place you can reach
System.out.println("The maximum place you can reach with given petrol : "
+ destin.floorEntry(petr));
}
}
输出:
The maximum place you can reach with given petrol : 10=Delhi
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