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Add Three Sum Problem (#2741)

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Sneha B 2021-10-28 22:31:59 +05:30 committed by GitHub
parent 6934c53c04
commit 9ff553e0a3
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2 changed files with 109 additions and 1 deletions
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109
Misc/ThreeSumProblem.java Normal file
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import java.util.*;
public class ThreeSumProblem {
public static void main(String args[])
{
Scanner scan = new Scanner(System.in);
System.out.print("Enter the target sum ");
int ts= scan.nextInt();
System.out.print("Enter the number of elements in the array ");
int n = scan.nextInt();
System.out.println("Enter all your array elements:");
int arr[]= new int[n];
for(int i=0;i<n;i++)
{
arr[i]=scan.nextInt();
}
ThreeSumProblem th = new ThreeSumProblem();
System.out.println("Brute Force Approach\n"+(th.BruteForce(arr,ts))+"\n");
System.out.println("Two Pointer Approach\n"+(th.TwoPointer(arr,ts))+"\n");
System.out.println("Hashmap Approach\n"+(th.Hashmap(arr,ts)));
}
public List<List<Integer>> BruteForce(int[] nums,int target) {
List<List<Integer>> arr = new ArrayList<List<Integer>>();
for(int i=0;i<nums.length;i++)
{
for(int j=i+1;j<nums.length;j++)
{
for(int k=j+1;k<nums.length;k++)
{
if(nums[i]+nums[j]+nums[k]==target)
{ List<Integer> temp = new ArrayList<>();
temp.add(nums[i]);
temp.add(nums[j]);
temp.add(nums[k]);
Collections.sort(temp);
arr.add(temp);
}
}
}
}
arr = new ArrayList<List<Integer>>(new LinkedHashSet<List<Integer>>(arr));
return arr;
}
public List<List<Integer>> TwoPointer(int[] nums, int target) {
Arrays.sort(nums);
List<List<Integer>> arr = new ArrayList<List<Integer>>();
int start=0;
int end=0;
int i = 0;
while(i<nums.length-1)
{
start=i+1;
end=nums.length-1;
while (start<end)
{
if (nums[start]+nums[end]+nums[i]==target)
{
List<Integer> temp = new ArrayList<>();
temp.add(nums[i]);
temp.add(nums[start]);
temp.add(nums[end]);
arr.add(temp);
start++;
end--;
}
else if (nums[start]+nums[end]+nums[i]<target)
start+=1;
else
end-=1;
}
i++;
}
Set<List<Integer>> set = new LinkedHashSet<List<Integer>>(arr);
return new ArrayList<List<Integer>>(set);
}
public List<List<Integer>> Hashmap(int[] nums, int target) {
Arrays.sort(nums);
Set<List<Integer>> ts = new HashSet();
HashMap<Integer,Integer> hm = new HashMap<>();
for(int i=0;i<nums.length;i++)
{
hm.put(nums[i],i);
}
for(int i=0;i<nums.length;i++)
{
for(int j=i+1;j<nums.length;j++)
{
int t= target - nums[i] - nums[j];
if(hm.containsKey(t) && hm.get(t)>j)
{
List<Integer> temp = new ArrayList<>();
temp.add(nums[i]);
temp.add(nums[j]);
temp.add(t);
ts.add(temp);
}
}
}
return new ArrayList(ts);
}
}

1
Misc/TwoSumProblem.java
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package Misc;
import java.util.*;
import java.util.stream.Collectors;