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gray_code.cc
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gray_code.cc
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#include <algorithm>
#include <string>
#include <vector>
#include "test_framework/generic_test.h"
#include "test_framework/test_failure.h"
#include "test_framework/timed_executor.h"
using std::vector;
vector<int> GrayCode(int num_bits) {
// Implement this placeholder.
return {};
}
bool DiffersByOneBit(int x, int y) {
int bit_difference = x ^ y;
return bit_difference && !(bit_difference & (bit_difference - 1));
}
void GrayCodeWrapper(TimedExecutor& executor, int num_bits) {
vector<int> result = executor.Run([&] { return GrayCode(num_bits); });
int expected_size = (1 << num_bits);
if (result.size() != expected_size) {
throw TestFailure("Length mismatch: expected " +
std::to_string(expected_size) + ", got " +
std::to_string(result.size()));
}
for (size_t i = 1; i < result.size(); i++)
if (!DiffersByOneBit(result[i - 1], result[i])) {
if (result[i - 1] == result[i]) {
throw TestFailure("Two adjacent entries are equal");
} else {
throw TestFailure("Two adjacent entries differ by more than 1 bit");
}
}
std::sort(begin(result), end(result));
auto uniq = std::unique(begin(result), end(result));
if (uniq != end(result)) {
throw TestFailure("Not all entries are distinct: found " +
std::to_string(std::distance(uniq, end(result))) +
" duplicates");
}
}
int main(int argc, char* argv[]) {
std::vector<std::string> args{argv + 1, argv + argc};
std::vector<std::string> param_names{"executor", "num_bits"};
return GenericTestMain(args, "gray_code.tsv", &GrayCodeWrapper,
DefaultComparator{}, param_names);
}