Add decoding and printout to resistant set monotonicity fingerprint class.

Author: kristomu

src/design/resistant/monotone.cc

@@ -1,3 +1,4 @@
+#include <stdexcept>
 #include <iostream>
 #include <numeric>
 #include <vector>
@@ -33,39 +34,66 @@ typedef std::vector<size_t>::const_iterator it;
 class subelections {
 	private:
 		bool add_subelection(combo::it begin, combo::it end);
+		size_t numcands;
 
 	public:
 		std::vector<std::vector<size_t> > subelection_members;
-		std::vector<size_t> max_options;
-		subelections(size_t numcands);
+		std::vector<std::vector<bool> > is_subelection_member;
+
+		std::vector<size_t> num_options;
+		size_t distinct_fingerprints;
+
+		subelections(size_t numcands_in);
 
 		size_t get_num_fingerprint_indices() const;
 };
 
 bool subelections::add_subelection(combo::it begin, combo::it end) {
 	subelection_members.push_back(std::vector<size_t>(begin, end));
 	size_t num_members = end-begin;
-	max_options.push_back((1<<num_members) - 2);
+	num_options.push_back((1<<num_members) - 2);
+
+	// Also add a vector where is_member[x] is true if the xth
+	// candidate is a part of this subelection.
+	std::vector<bool> is_member(numcands, false);
+
+	for (combo::it pos = begin; pos != end; ++pos) {
+		is_member[*pos] = true;
+	}
 
 	return false;
 }
 
-subelections::subelections(size_t numcands) {
+subelections::subelections(size_t numcands_in) {
+
+	numcands = numcands_in;
+
+	size_t i;
 
 	// Curry the implicit reference to the calling object.
 	auto this_add_subelection = [this](combo::it begin,
 	combo::it end) {
 		return add_subelection(begin, end);
 	};
 
-	for (size_t i = 2; i <= numcands; ++i) {
+	for (i = 2; i <= numcands; ++i) {
 		// Add every sub-election of i candidates.
 		std::vector<size_t> cands(numcands, 0);
 		std::iota(cands.begin(), cands.end(), 0);
 
 		for_each_combination(cands.begin(), cands.begin() + i,
 			cands.end(), this_add_subelection);
 	}
+
+	// Calculate the number of distinct fingerprints
+	// based on the number of subelections and the number
+	// of ways candidates can be chosen within each.
+
+	distinct_fingerprints = 1;
+
+	for (i = 0; i < num_options.size(); ++i) {
+		distinct_fingerprints *= num_options[i];
+	}
 }
 
 
@@ -80,15 +108,90 @@ class fingerprint {
 	public:
 		std::vector<std::vector<size_t> > above_quota;
 
-		void decode(size_t index);
+		void decode(const subelections & se, size_t index);
 		size_t encode() const;
+		void print(const subelections & se) const;
 };
 
-int main() {
+void fingerprint::decode(const subelections & se, size_t index) {
 
-	size_t numcands = 3;
+	if (index >= se.distinct_fingerprints) {
+		throw std::invalid_argument("index exceeds number of fingerprints!");
+	}
+
+	for (size_t subelec_idx = 0; subelec_idx < se.num_options.size();
+		++subelec_idx) {
+		// Get the index to apply to this particular subelection.
+		size_t num_options = se.num_options[subelec_idx];
+		size_t digit = index % num_options;
+
+		// Then decode it.
+		size_t num_members = se.subelection_members[subelec_idx].size();
+		std::vector<size_t> candidates_above_quota;
+
+		// Since at least one candidate must exceed the quota,
+		// an index of zero, which would correspond to an all-false
+		// vector, is disallowed.
+		++digit;
+
+		for (size_t member_idx = 0; member_idx < num_members; ++member_idx) {
+			if (digit % 2 == 1) {
+				candidates_above_quota.push_back(
+					se.subelection_members[subelec_idx][member_idx]);
+			}
+			digit >>= 1;
+		}
+
+		above_quota.push_back(candidates_above_quota);
+
+		std::cout << digit << " of " << num_options << "\n";
+		index /= num_options;
+	}
+}
 
+void fingerprint::print(const subelections & se) const {
+	size_t i;
+
+	for (size_t subelec_idx = 0; subelec_idx < se.num_options.size();
+		++subelec_idx) {
+
+		std::cout << "Subelection {";
+
+		for (i = 0; i < se.subelection_members[subelec_idx].size();
+			++i) {
+			if (i != 0) {
+				std::cout << ", ";
+			}
+			std::cout << (char)('A' + se.subelection_members[
+						subelec_idx][i]);
+		}
+
+		std::cout << "}: above quota: ";
+
+		for (i = 0; i < above_quota[subelec_idx].size(); ++i) {
+			if (i != 0) {
+				std::cout << ", ";
+			}
+
+			std::cout << (char)('A' + above_quota[subelec_idx][i]);
+		}
+
+		std::cout << "\n";
+	}
+}
+
+int main() {
+
+	size_t numcands = 4;
 	subelections se(numcands);
 
+	fingerprint test;
+
+	std::cout << "Number of distinct fingerprints: "
+		<< se.distinct_fingerprints << "\n";
+
+	test.decode(se, 19001);
+	test.print(se);
+
 	return 0;
 }