Merge cc2cdce into 54f0da8

README.md

@@ -385,4 +385,5 @@ problems from
 * [Day 390](https://github.com/vaskoz/dailycodingproblem-go/issues/783)
 * [Day 391](https://github.com/vaskoz/dailycodingproblem-go/issues/785)
 * [Day 392](https://github.com/vaskoz/dailycodingproblem-go/issues/787)
+* [Day 393](https://github.com/vaskoz/dailycodingproblem-go/issues/789)
 

day393/problem.go

@@ -0,0 +1,40 @@
+package day393
+
+// LargestRangeBrute returns the largest range of integers
+// using brute force.
+// Runtime is O(N*K) where K is the length of the longest range.
+// Effectively, this is O(N^2).
+// Converts the input into a hash set.
+func LargestRangeBrute(nums []int) (int, int) {
+	if n := len(nums); n == 0 {
+		return 0, 0
+	} else if n == 1 {
+		return nums[0], nums[0]
+	}
+
+	set := make(map[int]struct{}, len(nums))
+
+	for _, num := range nums {
+		set[num] = struct{}{}
+	}
+
+	var longest, sAns, eAns int
+
+	for start := range set {
+		count := 1
+		ptr := start + 1
+
+		for _, found := set[ptr]; found; _, found = set[ptr] {
+			count++
+			ptr++
+		}
+
+		if count > longest || (count == longest && start < sAns) {
+			longest = count
+			sAns = start
+			eAns = ptr - 1
+		}
+	}
+
+	return sAns, eAns
+}

day393/problem_test.go

@@ -0,0 +1,33 @@
+package day393
+
+import "testing"
+
+// nolint
+var testcases = []struct {
+	nums       []int
+	start, end int
+}{
+	{[]int{9, 6, 1, 3, 8, 10, 12, 11}, 8, 12},
+	{[]int{}, 0, 0},
+	{nil, 0, 0},
+	{[]int{12}, 12, 12},
+	{[]int{9, 1, 3, 8, 10, 12, 11, 2, 4, 5}, 1, 5},
+}
+
+func TestLargestRangeBrute(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range testcases {
+		if s, e := LargestRangeBrute(tc.nums); s != tc.start || e != tc.end {
+			t.Errorf("Expected (%v,%v), got (%v,%v)", tc.start, tc.end, s, e)
+		}
+	}
+}
+
+func BenchmarkLargestRangeBrute(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			LargestRangeBrute(tc.nums)
+		}
+	}
+}