Merge 3997d84 into 50f4261

README.md

@@ -247,3 +247,4 @@ problems from
 * [Day 236](https://github.com/vaskoz/dailycodingproblem-go/issues/485)
 * [Day 237](https://github.com/vaskoz/dailycodingproblem-go/issues/487)
 * [Day 238](https://github.com/vaskoz/dailycodingproblem-go/issues/489)
+* [Day 241](https://github.com/vaskoz/dailycodingproblem-go/issues/493)

day241/problem.go

@@ -0,0 +1,20 @@
+package day241
+
+import "sort"
+
+// HIndex returns the H-Index of the citations from an author.
+// Runs in O(N log N) using O(N) extra memory because we
+// don't want to mutate the original data by sorting.
+func HIndex(citations []int) int {
+	copied := make([]int, len(citations))
+	copy(copied, citations)
+	sort.Slice(copied, func(i, j int) bool {
+		return copied[i] > copied[j]
+	})
+	for paper, citationCount := range copied {
+		if citationCount < paper+1 {
+			return paper
+		}
+	}
+	return len(copied)
+}

day241/problem_test.go

@@ -0,0 +1,28 @@
+package day241
+
+import "testing"
+
+var testcases = []struct {
+	citations []int
+	hindex    int
+}{
+	{[]int{4, 3, 0, 1, 5}, 3},
+	{[]int{10}, 1},
+}
+
+func TestHIndex(t *testing.T) {
+	t.Parallel()
+	for _, tc := range testcases {
+		if result := HIndex(tc.citations); result != tc.hindex {
+			t.Errorf("Expected %v, got %v", tc.hindex, result)
+		}
+	}
+}
+
+func BenchmarkHIndex(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			HIndex(tc.citations)
+		}
+	}
+}