Given a collection of Intervals, the task is to merge all of the overlapping Intervals. [🔗Goto](https://practice.geeksforgeeks.org/problems/8a644e94faaa94968d8665ba9e0a80d1ae3e0a2d/1/?page=1&difficulty[]=1&status[]=unsolved&company[]=Microsoft&category[]=Arrays&category[]=Strings&sortBy=accuracy#)

<details>

<summary>Full Code</summary>

import java.util.*;

import java.lang.*;

import java.io.*;

class GFG

{

public static void main(String[] args) throws IOException

{

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int T = Integer.parseInt(br.readLine().trim());

while(T-->0)

{

int n = Integer.parseInt(br.readLine().trim());

String[] s = br.readLine().trim().split(" ");

int[][] Intervals = new int[n][2];

int j = 0;

for(int i = 0; i < n; i++){

Intervals[i][0] = Integer.parseInt(s[j]);

j++;

Intervals[i][1] = Integer.parseInt(s[j]);

j++;

}

Solution obj = new Solution();

int[][] ans = obj.overlappedInterval(Intervals);

for(int i = 0; i < ans.length; i++){

for(j = 0; j < ans[i].length; j++){

System.out.print(ans[i][j] + " ");

}

}

System.out.println();

}

}

}

</details>

class Solution

{

public int[][] overlappedInterval(int[][] Intervals)

{

//sort according the first element

Arrays.sort(Intervals, new Comparator<int []>(){

public int compare(int []arr1,int []arr2){

return arr1[0] - arr2[0];

}

});

Stack<int[]> st = new Stack<>();

//Iterate for each eleemnt and push into stack

for(int[] arr:Intervals){

//if stack is empty then push first element

if(st.empty()){

st.push(arr);

}

else{

int [] temp = st.peek();

//for a different range add the new range

if(temp[1]<arr[0]){

st.push(arr);

}

// If range overlapps then modify the 2nd element

else if(temp[1]>=arr[0] && temp[1] < arr[1]){

int []popped = st.pop();

popped[1] = arr[1];

st.push(popped);

}

}

}

int ans[][]=new int[st.size()][2];

int i = 0;

// Convert Stack Element into Array

for(int[]arr : st){

ans[i] = arr;

i++;

}

return ans;

}

}