add new solutions

solutions/7/q762/solution.go

@@ -0,0 +1,34 @@
+package q762
+
+var isPrime = [21]bool{}
+
+func init() {
+	for _, n := range []int{
+		2, 3, 5, 7, 11, 13, 17, 19,
+	} {
+		isPrime[n] = true
+	}
+}
+
+func count1s(n int) int {
+	cnt := 0
+	for n > 0 {
+		if n%2 == 1 {
+			cnt++
+		}
+		n >>= 1
+	}
+	return cnt
+}
+
+func countPrimeSetBits(left, right int) int {
+	cnt := 0
+	for n := left; n <= right; n++ {
+		if isPrime[count1s(n)] {
+			cnt++
+		}
+	}
+	return cnt
+}
+
+var _ = countPrimeSetBits