Write a program to find the sum of the first 1000 prime numbers
package com.primesum;
public class Main
{
public static void main(String args[])
{
int number = 2;
int count = 0;
long sum = 0;
while(count
< 1000)
{
if(isPrimeNumber(number))
{
sum
+= number;
count++;
}
number++;
}
System.out.println(sum);
}
private static boolean isPrimeNumber(int number)
{
for(int i=2; i<=number/2;
i++)
{
if(number
% i == 0)
{
return false;
}
}
return true;
}
}
Find longest substring without repeating characters
package com.java2novice.algos;
import java.util.HashSet;
import java.util.Set;
public class MyLongestSubstr
{
private
Set subStrList = new HashSet();
private int
finalSubStrSize = 0;
public Set
getLongestSubstr(String input)
{
subStrList.clear();
finalSubStrSize
= 0;
boolean[]
flag = new boolean[256];
int
j = 0;
char[]
inputCharArr = input.toCharArray();
for
(int i = 0; i < inputCharArr.length; i++)
{
char
c = inputCharArr[i];
if
(flag[c])
{
extractSubString(inputCharArr,j,i);
for
(int k = j; k < i; k++)
{
if
(inputCharArr[k] == c)
{
j
= k + 1;
break;
}
flag[inputCharArr[k]]
= false;
}
}
else
{
flag[c]
= true;
}
}
extractSubString(inputCharArr,j,inputCharArr.length);
return
subStrList;
}
private String
extractSubString(char[] inputArr, int start, int end)
{
StringBuilder
sb = new StringBuilder();
for(int
i=start;i
{
sb.append(inputArr[i]);
}
String
subStr = sb.toString();
if(subStr.length()
> finalSubStrSize)
{
finalSubStrSize
= subStr.length();
subStrList.clear();
subStrList.add(subStr);
}
else
if(subStr.length() == finalSubStrSize)
{
subStrList.add(subStr);
}
return
sb.toString();
}
public
static void main(String a[])
{
MyLongestSubstr
mls = new MyLongestSubstr();
System.out.println(mls.getLongestSubstr("java2novice"));
System.out.println(mls.getLongestSubstr("java_language_is_sweet"));
System.out.println(mls.getLongestSubstr("java_java_java_java"));
System.out.println(mls.getLongestSubstr("abcabcbb"));
}
}
Write a program to remove duplicates from sorted array
package com.java2novice.algos;
public class MyDuplicateElements
{
public static int[]
removeDuplicates(int[] input)
{
int j = 0;
int i = 1;
if(input.length
< 2)
{
return input;
}
while(i
< input.length)
{
if(input[i]
== input[j])
{
i++;
}else{
input[++j]
= input[i++];
}
}
int[]
output = new int[j+1];
for(int k=0;
k
{
output[k]
= input[k];
}
return output;
}
public static void main(String a[])
{
int[]
input1 = {2,3,6,6,8,9,10,10,10,12,12};
int[]
output = removeDuplicates(input1);
for(int i:output)
{
System.out.print(i+"
");
}
}
}
Simple JUnit test using Test annotation
package
com.java2novice.junit.tests;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
import
com.java2novice.junit.samples.MyEvenOdd;
public class MyEvenOddTest
{
public void testEvenOddNumber()
{
MyEvenOdd
meo = new MyEvenOdd();
assertEquals("10
is a even number", true, meo.isEvenNumber(10));
}
}
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