A: Count Largest Group

Author: Shuo

problems/count-largest-group/count_largest_group.go

@@ -0,0 +1,21 @@
+package problem1399
+
+func countLargestGroup(n int) int {
+	group := make(map[int]int)
+	for i := 1; i <= n; i++ {
+		s := 0
+		for x := i; x > 0; x /= 10 {
+			s += x % 10
+		}
+		group[s]++
+	}
+	ans, max := 0, 0
+	for _, v := range group {
+		if v == max {
+			ans++
+		} else if v > max {
+			ans, max = 1, v
+		}
+	}
+	return ans
+}

problems/count-largest-group/count_largest_group_test.go

@@ -0,0 +1,35 @@
+package problem1399
+
+import "testing"
+
+type testType struct {
+	in   int
+	want int
+}
+
+func TestCountLargestGroup(t *testing.T) {
+	tests := [...]testType{
+		{
+			in:   13,
+			want: 4,
+		},
+		{
+			in:   2,
+			want: 2,
+		},
+		{
+			in:   15,
+			want: 6,
+		},
+		{
+			in:   24,
+			want: 5,
+		},
+	}
+	for _, tt := range tests {
+		got := countLargestGroup(tt.in)
+		if got != tt.want {
+			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
+		}
+	}
+}