diff --git a/best-time-to-buy-and-sell-stock/invidam.go b/best-time-to-buy-and-sell-stock/invidam.go
new file mode 100644
index 000000000..55671947e
--- /dev/null
+++ b/best-time-to-buy-and-sell-stock/invidam.go
@@ -0,0 +1,10 @@
+func maxProfit(prices []int) int {
+	purchasePrice := prices[0]
+	maxBenefit := 0
+
+	for _, price := range prices {
+		purchasePrice = min(purchasePrice, price)
+		maxBenefit = max(maxBenefit, price-purchasePrice)
+	}
+	return maxBenefit
+}
diff --git a/contains-duplicate/invidam.go b/contains-duplicate/invidam.go
new file mode 100644
index 000000000..9816d1f0c
--- /dev/null
+++ b/contains-duplicate/invidam.go
@@ -0,0 +1,9 @@
+func containsDuplicate(nums []int) bool {
+	appeared := make(map[int]bool)
+
+	for _, num := range nums {
+		appeared[num] = true
+	}
+
+	return len(appeared) != len(nums)
+}
diff --git a/two-sum/invidam.go b/two-sum/invidam.go
new file mode 100644
index 000000000..b8956d26b
--- /dev/null
+++ b/two-sum/invidam.go
@@ -0,0 +1,10 @@
+func twoSum(nums []int, target int) []int {
+	need := make(map[int]int, len(nums))
+	for i, n := range nums {
+		if j, ok := need[n]; ok {
+			return []int{i, j}
+		}
+		need[target-n] = i
+	}
+	return nil
+}
diff --git a/valid-anagram/invidam.go b/valid-anagram/invidam.go
new file mode 100644
index 000000000..5eb713bba
--- /dev/null
+++ b/valid-anagram/invidam.go
@@ -0,0 +1,23 @@
+func isAnagram(s string, t string) bool {
+	freqS := make(map[rune]int, 26)
+	freqT := make(map[rune]int, 26)
+
+	for _, ch := range s {
+		if _, ok := freqS[ch]; ok {
+			freqS[ch]++
+		} else {
+			freqS[ch] = 1
+		}
+	}
+	for _, ch := range t {
+		freqT[ch]++
+	}
+
+	for ch := 'a'; ch <= 'z'; ch++ {
+		if diff := freqS[ch] - freqT[ch]; diff != 0 {
+			return false
+		}
+	}
+
+	return true
+}
diff --git a/valid-palindrome/invidam.go b/valid-palindrome/invidam.go
new file mode 100644
index 000000000..ad1acb0eb
--- /dev/null
+++ b/valid-palindrome/invidam.go
@@ -0,0 +1,15 @@
+func isPalindrome(s string) bool {
+	filtered := strings.Map(func(r rune) rune {
+		if !unicode.IsLetter(r) && !unicode.IsNumber(r) {
+			return -1
+		}
+		return unicode.ToLower(r)
+	}, s)
+
+	for ldx, rdx := 0, len(filtered) - 1; ldx < rdx; ldx, rdx = ldx + 1, rdx - 1 {
+		if filtered[ldx] != filtered[rdx] {
+			return false
+		}
+	}
+	return true
+}