feat(LeetCode #14): add Longest Common Prefix solution

LeetCode/problem014_LongestCommonPrefix.go

@@ -0,0 +1,29 @@
+/*
+Problem 14. Longest Common Prefix
+*/
+
+package leetcode
+
+// Time complexity:  O(n*m)
+// Space complexity: O(1)
+func longestCommonPrefix(strs []string) string {
+	// Edge case: if the input array is empty, return an empty string.
+	if len(strs) == 0 {
+		return ""
+	}
+
+	prefix := strs[0]
+
+	for _, s := range strs[1:] {
+		j := 0
+		for j < len(prefix) && j < len(s) && prefix[j] == s[j] {
+			j++
+		}
+		prefix = prefix[:j]
+		if prefix == "" {
+			return ""
+		}
+	}
+
+	return prefix
+}

LeetCode/problem014_LongestCommonPrefix_test.go

@@ -0,0 +1,48 @@
+package leetcode
+
+import (
+	"testing"
+)
+
+func TestLongestCommonPrefix(t *testing.T) {
+	var tests = []struct {
+		name   string
+		input  []string
+		output string
+	}{
+		{
+			name:   "Example 1",
+			input:  []string{"flower", "flow", "flight"},
+			output: "fl",
+		},
+		{
+			name:   "Example 2",
+			input:  []string{"dog", "racecar", "car"},
+			output: "",
+		},
+		{
+			name:   "All strings identical",
+			input:  []string{"test", "test", "test"},
+			output: "test",
+		},
+		{
+			name:   "Single string in array",
+			input:  []string{"single"},
+			output: "single",
+		},
+		{
+			name:   "Empty array",
+			input:  []string{},
+			output: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := longestCommonPrefix(tt.input)
+			if result != tt.output {
+				t.Errorf("longestCommonPrefix(%v) = %q; expected %q", tt.input, result, tt.output)
+			}
+		})
+	}
+}