add new solutions

solutions/1/q137/solution.go

@@ -0,0 +1,22 @@
+package q137
+
+func singleNumber(nums []int) int {
+	bitCounts := make([]uint8, 32)
+	for _, num := range nums {
+		num32 := int32(num)
+		for i := range 32 {
+			if num32|1<<i == num32 {
+				bitCounts[i] = (bitCounts[i] + 1) % 3
+			}
+		}
+	}
+	var ret int32
+	for i := range 32 {
+		if bitCounts[i] != 0 {
+			ret |= 1 << i
+		}
+	}
+	return int(ret)
+}
+
+var _ = singleNumber