Add bisect utility

This is too common of an optimization to not have this readily accessible. And I kinda like how this worked out, too. Go is fun.

utilities/bisect.go

@@ -0,0 +1,31 @@
+package utilities
+
+import "math"
+
+// Bisect takes a known-good low and known-bad high value as the bounds
+// to bisect, and a function to test each value for success or failure.
+// If the function succeeds, the value is adjusted toward the maximum,
+// and if the function fails, the value is adjusted toward the minimum.
+// The final value is returned when the difference between the success
+// and the failure is less than or equal to the acceptance threshold
+// (usually 1, for integers).
+func Bisect[T Number](low, high, threshold T, tryFunc func(val T) bool) T {
+	lastSuccess := low
+	lastFailure := high
+	currVal := low
+
+	for T(math.Abs(float64(lastFailure-lastSuccess))) > threshold {
+		success := tryFunc(currVal)
+		adjustment := (lastFailure - lastSuccess) / 2
+		if success {
+			lastSuccess = currVal
+		} else {
+			lastFailure = currVal
+			adjustment = -adjustment
+		}
+
+		currVal += adjustment
+	}
+
+	return currVal
+}