1 . Count occurrences of elements of list in Java
import
java.util.HashMap;
import
java.util.TreeMap;
public class CountOccurrences {
public static void main(String[] args) {
String str[] = {"Rahul", "Trupti", "Rahul",
"Yatin", "Keyur", "Yatin", "Manoj",
"Yatin", "Trupti"};
countOccurrencesName(str);
}
private static void countOccurrencesName(String[] str) {
HashMap<String, Integer> map = new HashMap<>();
for (int i = 0; i < str.length; i++) {
String ch = str[i];
if (map.get(ch) != null) {
map.put(ch, map.get(ch) + 1);
} else {
map.put(ch, 1);
}
}
TreeMap<String, Integer> t = new
TreeMap<>(map);
System.out.println(t);
}
}
Output :
{Keyur=1,
Manoj=1, Rahul=2, Trupti=2, Yatin=3}
2.Count Occurrences of a Char in a String
import
java.util.HashMap;
public
class CountOccurrencesChar {
public static void main(String[] args) {
String ch = "Chaudhari Rahul";
char[] ch1 = ch.toCharArray();
HashMap<Character, Integer> map = new HashMap<>();
for (int i = 0; i < ch1.length - 1; i++) {
char c = ch1[i];
if (map.containsKey(c)) {
map.put(c, map.get(c) + 1);
} else {
map.put(c, 1);
}
}
System.out.println(map);
}
}
Output :
{ =1, a=3, r=1, R=1, C=1, d=1, u=2, h=3, i=1}
3.Find
the element which appears maximum number of times in the array.
import
java.util.ArrayList;
import
java.util.Collections;
public
class RepeatedMaxNo {
public
static void main(String[] args) {
int
num[] = {99, 77, 07, 99, 007, 99, 01, 66, 99};
int
result = countRepeateNo(num);
System.out.println("Max
Repeated Number : " + result);
}
public
static int countRepeateNo(int[] num) {
ArrayList<Integer>
list = new ArrayList<>();
int
count = 0;
boolean
flag = false;
for
(int i = 0; i < num.length; i++) {
for
(int j = i + 1; j < num.length - 1; j++) {
if
(num[i] == num[j]) {
count++;
flag
= true;
}
}
if
(flag == true) {
list.add(count
+ 1);
count
= 0;
max
= (Integer) Collections.max(list);
}
}
return
max;
}
}
Output :
Max Repeated Number : 3
One More
public
class MaxRepeatingBruteForce {
public void MaxRepeatingElement(int[] arrA) {
int maxCounter = 0;
int element = 0;
for (int i = 0; i < arrA.length; i++) {
int counter = 1;
for (int j = i + 1; j < arrA.length; j++) {
if (arrA[i] == arrA[j]) {
counter++;
}
}
if (maxCounter < counter) {
maxCounter = counter;
element = arrA[i];
}
}
System.out.println("Element repeating maximum no of times: " +
element + ", maximum count: " + maxCounter);
}
public static void main(String[] args) {
int[] arrA = {4, 1, 5, 2, 1, 5, 9, 8, 6, 5, 3, 2, 4, 7};
MaxRepeatingBruteForce m = new MaxRepeatingBruteForce();
m.MaxRepeatingElement(arrA);
}
}
Output :
Element repeating maximum no of times: 5, maximum count: 3
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