added problem 523

Author: SHA65536

problems/problem0523/subarr_sum.go

@@ -0,0 +1,38 @@
+package problem0523
+
+/*
+Given an integer array nums and an integer k,
+return true if nums has a continuous subarray of size at least two whose elements sum up to a multiple of k, or false otherwise.
+An integer x is a multiple of k if there exists an integer n such that x = n * k. 0 is always a multiple of k.
+*/
+
+func checkSubarraySum(nums []int, k int) bool {
+	var sum int
+	for i := 0; i < len(nums)-1; i++ {
+		sum = nums[i]
+		for j := i + 1; j < len(nums); j++ {
+			sum += nums[j]
+			if sum%k == 0 {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func checkSubarraySumOpt(nums []int, k int) bool {
+	var seen = map[int]int{0: -1}
+	var sum int
+	for i := range nums {
+		sum += nums[i]
+		sum %= k
+		if prev, ok := seen[sum]; ok {
+			if i-prev > 1 {
+				return true
+			}
+		} else {
+			seen[sum] = i
+		}
+	}
+	return false
+}

problems/problem0523/subarr_sum_test.go

@@ -0,0 +1,57 @@
+package problem0523
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type Result struct {
+	Input    []int
+	Target   int
+	Expected bool
+}
+
+var Results = []Result{
+	{[]int{23, 2, 4, 6, 7}, 6, true},
+	{[]int{23, 2, 6, 4, 7}, 6, true},
+	{[]int{23, 2, 6, 4, 7}, 13, false},
+	{[]int{2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2}, 1751423, false},
+}
+
+func TestSubarraySumEqual(t *testing.T) {
+	assert := assert.New(t)
+
+	for _, res := range Results {
+		want := res.Expected
+		got := checkSubarraySum(res.Input, res.Target)
+		assert.Equal(want, got, fmt.Sprintf("%+v", res))
+	}
+}
+
+func BenchmarkSubarraySumEqual(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, res := range Results {
+			checkSubarraySum(res.Input, res.Target)
+		}
+	}
+}
+
+func TestSubarraySumEqualOpt(t *testing.T) {
+	assert := assert.New(t)
+
+	for _, res := range Results {
+		want := res.Expected
+		got := checkSubarraySumOpt(res.Input, res.Target)
+		assert.Equal(want, got, fmt.Sprintf("%+v", res))
+	}
+}
+
+func BenchmarkSubarraySumEqualOpt(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, res := range Results {
+			checkSubarraySumOpt(res.Input, res.Target)
+		}
+	}
+}

readme.md

@@ -124,6 +124,7 @@ Each problem is in it's own directory, with test files. There are helper package
 | 0501 | [Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree) | [My Solution](./problems/problem0501) | ✅ |
 | 0509 | [Fibonacci Number](https://leetcode.com/problems/fibonacci-number) | [My Solution](./problems/problem0509) | ✅ |
 | 0515 | [Find Largest Value in Each Tree Row](https://leetcode.com/problems/find-largest-value-in-each-tree-row) | [My Solution](./problems/problem0515) | ✅ |
+| 0523 | [Continuous Subarray Sum](https://leetcode.com/problems/continuous-subarray-sum) | [My Solution](./problems/problem0523) | ✅ |
 | 0539 | [Minimum Time Difference](https://leetcode.com/problems/minimum-time-difference) | [My Solution](./problems/problem0539) | ✅ |
 | 0542 | [01 Matrix](https://leetcode.com/problems/01-matrix) | [My Solution](./problems/problem0542) | ✅ |
 | 0543 | [Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree) | [My Solution](./problems/problem0543) | ✅ |