Revert "update vendor/"

This reverts commit 7ce522110e.

vendor/github.com/crillab/gophersat/solver/card.go

@@ -0,0 +1,27 @@
+package solver
+
+// A CardConstr is a cardinality constraint, i.e a set of literals (represented with integer variables) associated with a minimal number of literals that must be true.
+// A propositional clause (i.e a disjunction of literals) is a cardinality constraint with a minimal cardinality of 1.
+type CardConstr struct {
+	Lits    []int
+	AtLeast int
+}
+
+// AtLeast1 returns a cardinality constraint stating that at least one of the given lits must be true.
+// This is the equivalent of a propositional clause.
+func AtLeast1(lits ...int) CardConstr {
+	return CardConstr{Lits: lits, AtLeast: 1}
+}
+
+// AtMost1 returns a cardinality constraint stating that at most one of the given lits can be true.
+func AtMost1(lits ...int) CardConstr {
+	for i, lit := range lits {
+		lits[i] = -lit
+	}
+	return CardConstr{Lits: lits, AtLeast: len(lits) - 1}
+}
+
+// Exactly1 returns two cardinality constraints stating that exactly one of the given lits must be true.
+func Exactly1(lits ...int) []CardConstr {
+	return []CardConstr{AtLeast1(lits...), AtMost1(lits...)}
+}