Add 56. Merge Intervals

Author: LuaanNguyen

README.md

@@ -6,13 +6,11 @@ This repository contains my solutions to LeetCode problems in [Go](https://go.de
   <img src="https://raw.githubusercontent.com/gist/brudnak/6c21505423e4ff089ab704ec79b5a096/raw/b2d3dec32474b2121b179920734b259323a7c250/go.gif" alt="Go" width="400"/>
 </div>
 
-## Folder Structure 🗂️
-
 - `easy/`: Easy level problems.
 - `medium/`: Medium level problems.
 - `hard/`: Hard level problems.
 
-## Unit Testing 🧪
+## Testing 🧪
 
 In your root direction, run:
 
@@ -32,7 +30,7 @@ Clean test cache
 go clean -testcache
 ```
 
-## Solutions (Continue Updating...)
+<!-- ## Solutions (Continue Updating...)
 
 |                                                              Leetcode ID                                                              | Title & Solution                                                                                                            | Coefficient Of Difficulty |                                             Remarks                                              |                                                                                                        Approach                                                                                                        |
 | :-----------------------------------------------------------------------------------------------------------------------------------: | :-------------------------------------------------------------------------------------------------------------------------- | :-----------------------: | :----------------------------------------------------------------------------------------------: | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: |
@@ -60,7 +58,7 @@ go clean -testcache
 |                                 [680](https://leetcode.com/problems/valid-palindrome-ii/description/)                                 | [Valid Palindrome II](/easy/680_valid_palindrome_II)                                                                        |           easy            |                                         _`Two Pointers`_                                         |                                  Have a helper function which has the same structure as the main function. Use 2 pointers to check the +1 or -1 element whether they are equal or not                                  |
 |                                   [344](https://leetcode.com/problems/reverse-string/description/)                                    | [Reverse String](/easy/344_reverse_string)                                                                                  |           easy            |                                         _`Two Pointers`_                                         |                                                                                                                                                                                                                        |
 |                              [2843](https://leetcode.com/problems/count-symmetric-integers/description/)                              | [Count Symmetric Integers](/easy/2843_count_symmetric_integers)                                                             |           easy            |                                                                                                  |                                                                                                                                                                                                                        |
-|                                         [18](https://leetcode.com/problems/4sum/description/)                                         | [4Sum](/medium/18_4sum)                                                                                                     |          medium           |                                         _`Two pointers`_                                         |                                        Do Two Sum II and 3Sum first since 4Sum is the combination of those problems. There is an extra for loop. Make sure to check duplicates.                                        |
+|                                         [18](https://leetcode.com/problems/4sum/description/)                                         | [4Sum](/medium/18_4sum)                                                                                                     |          medium           |                                         _`Two pointers`_                                         |                                        Do Two Sum II and 3Sum first since 4Sum is the combination of those problems. There is an extra for loop. Make sure to check duplicates.                                        | -->
 
 ## Workflow 🌊
 
@@ -77,7 +75,7 @@ go clean -testcache
 - Update `README.md` with current stats
 - Automaticall commits and pushes the changes
 
-## Statistics 📊
+## Stats
 
 - Easy: 8 solutions
 - Medium: 17 solutions

medium/56_merge_intervals/56_merge_intervals.go

@@ -0,0 +1,34 @@
+package merge_intervals
+
+import (
+	"sort"
+)
+
+func merge(intervals [][]int) [][]int {
+	n := len(intervals)
+	res := [][]int{}
+
+	// Sort by starting index in each element 
+	sort.Slice(intervals, func(i, j int ) bool {
+		return intervals[i][0] < intervals[j][0]
+	})
+
+	i := 0 
+	for i < n {
+		start := intervals[i][0] 
+		end := intervals[i][1]
+		j := i + 1
+
+		for j < n && intervals[j][0] <= end {
+			if end < intervals[j][1] {
+				end = intervals[j][1]
+			}
+			j ++ 
+		}   
+
+		res = append(res, []int{start, end})
+		i = j
+	}
+
+	return res
+}

medium/56_merge_intervals/56_merge_intervals_test.go

@@ -0,0 +1,46 @@
+package merge_intervals
+
+import (
+	"reflect"
+	"testing"
+)
+
+
+func TestMerge(t *testing.T) {
+	tests := []struct {
+		name string
+		intervals [][]int
+		expectedResult [][]int  
+	} {
+		{
+			name: "Test Case 1",
+			intervals: [][]int{{1,3},{1,5},{6,7}},
+			expectedResult: [][]int{{1,5},{6,7}},
+		},
+		{
+			name: "Test Case 2",
+			intervals: [][]int{{1,3},{2,6},{8,10},{15,18}},
+			expectedResult: [][]int{{1,6},{8,10},{15,18}},
+		},
+		{
+			name: "Test Case 3",
+			intervals: [][]int{{1,4},{4,5}},
+			expectedResult: [][]int{{1,5}},
+		},
+		{
+			name: "Test Case 4 (edge case)",
+			intervals: [][]int{},
+			expectedResult: [][]int{},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got := merge(test.intervals)
+			if !reflect.DeepEqual(got, test.expectedResult) {
+				t.Errorf("Merge(%v) = %v; want = %v", test.intervals, got, test.expectedResult)
+			}
+		})
+
+	}
+}