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Array/MidIndexFinder/Problem.md

@@ -0,0 +1,37 @@
+# Problem: https://leetcode.com/problems/find-the-middle-index-in-array/
+```
+Given a 0-indexed integer array nums, find the leftmost middleIndex (i.e., the smallest amongst all the possible ones).
+
+A middleIndex is an index where nums[0] + nums[1] + ... + nums[middleIndex-1] == nums[middleIndex+1] + nums[middleIndex+2] + ... + nums[nums.length-1].
+
+If middleIndex == 0, the left side sum is considered to be 0. Similarly, if middleIndex == nums.length - 1, the right side sum is considered to be 0.
+
+Return the leftmost middleIndex that satisfies the condition, or -1 if there is no such index.
+
+
+
+Example 1:
+
+Input: nums = [2,3,-1,8,4]
+Output: 3
+Explanation: The sum of the numbers before index 3 is: 2 + 3 + -1 = 4
+The sum of the numbers after index 3 is: 4 = 4
+Example 2:
+
+Input: nums = [1,-1,4]
+Output: 2
+Explanation: The sum of the numbers before index 2 is: 1 + -1 = 0
+The sum of the numbers after index 2 is: 0
+Example 3:
+
+Input: nums = [2,5]
+Output: -1
+Explanation: There is no valid middleIndex.
+
+
+Constraints:
+
+1 <= nums.length <= 100
+-1000 <= nums[i] <= 1000
+
+```

Array/MidIndexFinder/go/MidIndexFinder.go

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+package _go
+
+func findMiddleIndex(nums []int) int {
+	sum, leftPrefixSum, rightPrefixSum := 0, 0, 0
+	for _, num := range nums {
+		sum += num
+	}
+	for i := 0; i < len(nums); i++ {
+		rightPrefixSum = sum - leftPrefixSum - nums[i]
+		if leftPrefixSum == rightPrefixSum {
+			return i
+		}
+		leftPrefixSum += nums[i]
+	}
+
+	return -1
+}

Array/MidIndexFinder/go/MidIndexFinder_test.go

@@ -0,0 +1,45 @@
+package _go
+
+import (
+	"testing"
+)
+
+func Test_findMiddleIndex(t *testing.T) {
+	type args struct {
+		nums []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "Test 1",
+			args: args{
+				nums: []int{2, 3, -1, 8, 4},
+			},
+			want: 3,
+		},
+		{
+			name: "Test 2",
+			args: args{
+				nums: []int{1, -1, 4},
+			},
+			want: 2,
+		},
+		{
+			name: "Test 3",
+			args: args{
+				nums: []int{2, 5},
+			},
+			want: -1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := findMiddleIndex(tt.args.nums); got != tt.want {
+				t.Errorf("findMiddleIndex() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

README.md

@@ -22,6 +22,7 @@ Most of these problems are solved using C++. My goal is to publish solutions for
 - [Check if the coordinates are in a straight line](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/LineChecker/Problem.md)
 - [Make Two Arrays Equal by Reversing Sub-arrays](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/MakeTwoArraysEqual/Problem.md)
 - [Merge N Sorted Arrays](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/MergeSortedArray/Problem.md)
+- [Find the middle index number of the array](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/MiddleIndex/Problem.md)
 - [Find the missing number from an array](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/MissingNumber.cpp)
 - [Find the missing ranges from an array](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/MissingRangeFinder.cpp)
 - [Move Zeroes](https://github.com/ravitandon90/LeetCode-TopProblems/blob/main/Array/MoveZeroes.cpp)