Add solution to project euler's problem 3

project_euler/problem3.qbl

@@ -0,0 +1,56 @@
+//valid,6857
+//:END:
+import "../std.qbl"
+
+600851475143 2 divHasLargerPF 3
+while
+{
+	// n p
+	req dup 2 req req +
+	// p n p+2
+	swp req
+	// n p p+2
+	divHasLargerPF
+	// p+2 hasLPF newN
+	req
+}
+deq 2 - intToStr println
+
+function int int => bool int divHasLargerPF
+{
+	req dup req divIfDivisible
+	// n newN
+	1 req dup
+	// newN 1 n newN
+	== req req
+	// is1 n newN
+	if
+	{
+		false req deq
+	}
+	else
+	{
+		true deq req
+	}
+}
+
+function int int => int divIfDivisible
+{
+	// p n
+	dup req dup swp
+	// p n p n
+	divmod 0
+	// p n p/n p%n 0
+	req req req ==
+	// p n p/n isDiv
+	req req req
+	if
+	{
+		deq req divIfDivisible
+	}
+	else
+	{
+		req deq deq
+	}
+}
+