feat(solutions): add maximum_subarray

Author: WindomZ

README.md

@@ -24,6 +24,7 @@
 
 | # | Problem | Solution | Difficulty | Single Repetition Duration | LeetCode Run Time |
 | ---: | :----- | :--------: | :----------: | ----------: | ----------: |
+|53|[Maximum Subarray][Solutions-53]|[WindomZ][Solutions-53-Go]|Easy|[10.3 ns/op/6 test cases][Solutions-53-Test]|12 ms|
 |50|[Pow(x, n)][Solutions-50]|[WindomZ][Solutions-50-Go]|Medium|[7.31 ns/op/12 test cases][Solutions-50-Test]|3 ms|
 |49|[Group Anagrams][Solutions-49]|[WindomZ][Solutions-49-Go]|Medium|[313 ns/op/3 test cases][Solutions-49-Test]|582 ms|
 |48|[Rotate Image][Solutions-48]|[WindomZ][Solutions-48-Go]|Medium|[12.1 ns/op/3 test cases][Solutions-48-Test]|3 ms|
@@ -103,6 +104,9 @@ Welcome to report bugs, suggest ideas and discuss on [issues page](https://githu
 ### Support
 If you like it then you can put a :star:Star on it.
 
+[Solutions-53-Test]:solutions/maximum_subarray/maxSubArray_test.go#L18
+[Solutions-53-Go]:solutions/maximum_subarray/maxSubArray.go
+[Solutions-53]:https://leetcode.com/maximum-subarray/
 [Solutions-50-Test]:solutions/powx_n/myPow_test.go#L26
 [Solutions-50-Go]:solutions/powx_n/myPow.go
 [Solutions-50]:https://leetcode.com/powx-n/

solutions/maximum_subarray/maxSubArray.go

@@ -0,0 +1,22 @@
+package maximumsubarray
+
+func maxSubArray(nums []int) int {
+	if len(nums) == 0 {
+		return 0
+	}
+	max, sum := nums[0], nums[0]
+	for i := 1; i < len(nums); i++ {
+		// get maximum value between the sum of the contiguous subarray and the current number
+		sum = maxInt(sum+nums[i], nums[i])
+		// get the largest sum
+		max = maxInt(max, sum)
+	}
+	return max
+}
+
+func maxInt(x, y int) int {
+	if x >= y {
+		return x
+	}
+	return y
+}

solutions/maximum_subarray/maxSubArray_test.go

@@ -0,0 +1,32 @@
+package maximumsubarray
+
+import (
+	"testing"
+
+	"github.com/WindomZ/testify/assert"
+)
+
+func Test_maxSubArray(t *testing.T) {
+	assert.Equal(t, 0, maxSubArray([]int{}))
+	assert.Equal(t, 7, maxSubArray([]int{1, 2, 3, -4, 5}))
+	assert.Equal(t, 6, maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4}))
+	assert.Equal(t, 14, maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4, 9, -6}))
+	assert.Equal(t, 18, maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4, 9, -6, 10, -12}))
+	assert.Equal(t, 10, maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4, -9, -6, 10, -12}))
+}
+
+func Benchmark_maxSubArray(b *testing.B) {
+	b.StopTimer()
+	b.ReportAllocs()
+	b.StartTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			maxSubArray([]int{})
+			maxSubArray([]int{1, 2, 3, -4, 5})
+			maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4})
+			maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4, 9, -6})
+			maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4, 9, -6, 10, -12})
+			maxSubArray([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4, -9, -6, 10, -12})
+		}
+	})
+}