diff --git a/problems/string-compression/string_compression.go b/problems/string-compression/string_compression.go
index 71c8f0565..2e1182538 100644
--- a/problems/string-compression/string_compression.go
+++ b/problems/string-compression/string_compression.go
@@ -1 +1,21 @@
 package string_compression
+
+import "strconv"
+
+func compress(chars []byte) int {
+	ans, anchor, l := 0, 0, len(chars)
+	for i, c := range chars {
+		if i == l-1 || c != chars[i+1] {
+			chars[ans] = chars[anchor]
+			ans++
+			if i> anchor {
+				for _, n := range strconv.Itoa(i - anchor + 1) {
+					chars[ans] = byte(n)
+					ans++
+				}
+			}
+			anchor = i + 1
+		}
+	}
+	return ans
+}
diff --git a/problems/string-compression/string_compression_test.go b/problems/string-compression/string_compression_test.go
index 71c8f0565..bf9f1426f 100644
--- a/problems/string-compression/string_compression_test.go
+++ b/problems/string-compression/string_compression_test.go
@@ -1 +1,38 @@
 package string_compression
+
+import (
+	"reflect"
+	"testing"
+)
+
+type caseType struct {
+	input []byte
+	expected []byte
+}
+
+func TestCompress(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input: []byte{'a', 'a', 'b', 'b', 'c', 'c', 'c'},
+			expected: []byte{'a', '2', 'b', '2', 'c', '3'},
+		},
+		{
+			input: []byte{'a'},
+			expected: []byte{'a'},
+		},
+		{
+			input: []byte{'a', 'a'},
+			expected: []byte{'a', '2'},
+		},
+		{
+			input: []byte{'a', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b', 'b'},
+			expected: []byte{'a', 'b', '1', '2'},
+		},
+	}
+	for _, tc := range tests {
+		l := compress(tc.input)
+		if !reflect.DeepEqual(tc.input[:l], tc.expected) {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, l, tc.expected)
+		}
+	}
+}
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