running sum

runningsum/readme.md

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+1480. Running Sum of 1d Array
+Easy
+
+Given an array nums. We define a running sum of an array as runningSum[i] = sum(nums[0]…nums[i]).
+
+Return the running sum of nums.
+
+ 
+
+Example 1:
+
+Input: nums = [1,2,3,4]
+Output: [1,3,6,10]
+Explanation: Running sum is obtained as follows: [1, 1+2, 1+2+3, 1+2+3+4].
+
+Example 2:
+
+Input: nums = [1,1,1,1,1]
+Output: [1,2,3,4,5]
+Explanation: Running sum is obtained as follows: [1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+1].
+
+Example 3:
+
+Input: nums = [3,1,2,10,1]
+Output: [3,4,6,16,17]
+
+ 
+
+Constraints:
+
+    1 <= nums.length <= 1000
+    -10^6 <= nums[i] <= 10^6

runningsum/runningsum.go

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+package runningsum
+
+func runningSum(nums []int) []int {
+	result := make([]int, len(nums))
+	total := 0
+	for i, num := range nums {
+		total += num
+		result[i] = total
+	}
+
+	return result
+}
+
+func RunningSum(nums []int) []int {
+	return runningSum(nums)
+}

runningsum/runningsum_test.go

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+package runningsum_test
+
+import (
+	"testing"
+
+	"git.jxs.me/leetgo/runningsum"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEmpty(t *testing.T) {
+	expected := make([]int, 0)
+	actual := runningsum.RunningSum([]int{})
+	require.Equal(t, expected, actual)
+}
+
+func TestSingle(t *testing.T) {
+	expected := []int{1}
+	actual := runningsum.RunningSum([]int{1})
+	require.Equal(t, expected, actual)
+}
+
+func TestDouble(t *testing.T) {
+	expected := []int{1, 2}
+	actual := runningsum.RunningSum([]int{1, 1})
+	require.Equal(t, expected, actual)
+}
+
+func TestExample1(t *testing.T) {
+	expected := []int{1, 3, 6, 10}
+	actual := runningsum.RunningSum([]int{1, 2, 3, 4})
+	require.Equal(t, expected, actual)
+}
+
+func TestExample2(t *testing.T) {
+	expected := []int{1, 2, 3, 4, 5}
+	actual := runningsum.RunningSum([]int{1, 1, 1, 1, 1})
+	require.Equal(t, expected, actual)
+}
+
+func TestExample3(t *testing.T) {
+	expected := []int{3, 4, 6, 16, 17}
+	actual := runningsum.RunningSum([]int{3, 1, 2, 10, 1})
+	require.Equal(t, expected, actual)
+}