Add problem 0007

go.mod

@@ -0,0 +1,3 @@
+module github.com/ordinary-dev/my-solutions
+
+go 1.19

leetcode/0007-reverse-integer/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+    "math"
+)
+
+func reverse(x int) int {
+    var res int32
+
+    var mul int32 = 1
+    if x < 0 {
+        mul = -1
+        x *= -1
+    }
+
+    for x != 0 {
+        digit := mul * int32(x % 10)
+        if mul > 0 && (math.MaxInt32 - digit) / 10 < res {
+            return 0
+        }
+        if mul < 0 && (math.MinInt32 - digit) / 10 > res {
+            return 0
+        }
+
+        res = res * 10 + digit
+        x /= 10
+    }
+
+    return int(res)
+}

leetcode/0007-reverse-integer/main_test.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+    "testing"
+    "math"
+)
+
+func TestReverse(t *testing.T) {
+    if res := reverse(123); res != 321 {
+        t.Fatalf("%v != 321", res)
+    }
+    if res := reverse(-123); res != -321 {
+        t.Fatalf("%v != -321", res)
+    }
+    if res := reverse(120); res != 21 {
+        t.Fatalf("%v != 12", res)
+    }
+    if res := reverse(math.MaxInt32); res != 0 {
+        t.Fatalf("%v != 0", res)
+    }
+}

readme.md

@@ -16,6 +16,13 @@ cd random-problem
 ruby test.rb
 ```
 
+Go:
+
+```bash
+cd random-problem
+go test ./...
+```
+
 ## Why Ruby?
 
 Solving problems in Ruby can be a lot more fun than it first appears.
@@ -23,3 +30,7 @@ It is relatively slow language.
 Sub-optimal C or Rust solutions will pass all tests,
 but Ruby or Python solutions will not be able to meet the time limit.
 This forces us to look for optimized algorithms.
+
+## Why Go?
+
+Go is used when stronger typing is required. This helps not to violate the conditions of the task.