go: add «334. Increasing Triplet Sequence»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/increasing-triplet-subsequence.go

@@ -0,0 +1,18 @@
+package main
+
+import "math"
+
+func increasingTriplet(nums []int) bool {
+	a, b := math.MaxInt, math.MaxInt
+	for _, x := range nums {
+		if x <= a {
+			a = x
+		} else if x <= b {
+			b = x
+		} else {
+			return true
+		}
+	}
+
+	return false
+}