Reduce complexity of division and fix pow function to properly return for negative exponents

bigint.h

@@ -284,6 +284,7 @@ namespace BigInt {
         friend std::hash<bigint>;
 
         static bigint pow(const bigint& base, const bigint& exponent) {
+            if (exponent < 0) return 0;
             if (exponent == 0) return 1;
             if (exponent == 1) return base;
 
@@ -643,28 +644,22 @@ namespace BigInt {
         bigint remainder = numerator;
         bigint quotient = 0;
 
-        auto count = count_digits(remainder) - count_digits(denominator) - 1;
+        while (remainder >= denominator) {
+            int count = count_digits(remainder) - count_digits(denominator) - 1;
 
-        auto numerator_size = pow(10, count);
-
-        auto temp = denominator * numerator_size;
-
-        while (denominator * numerator_size < remainder) {
-            temp = denominator * numerator_size;
-            remainder -= temp;
-            quotient += numerator_size;
-            count = count_digits(remainder) - count_digits(denominator) - 1;
+            // Prevent negative exponents which cause pow() to return 0
+            if (count < 0) {
+                count = 0;
+            }
 
+            bigint numerator_size = pow(10, count);
+            bigint temp = denominator * numerator_size;
 
-            if (numerator_size <= 1) {
-                quotient += remainder / denominator;
-                break;
-            }
-            if (remainder.vec.size() <= 1) {
-                quotient += remainder.vec.back() / denominator.vec.back();
-                break;
+            // Repeatedly subtract the chunk from the remainder
+            while (remainder >= temp) {
+                remainder -= temp;
+                quotient += numerator_size;
             }
-            numerator_size = pow(10, count);
         }
 
         return quotient;

tests/test.cpp

@@ -74,8 +74,8 @@ static auto measure_execution = [](const int count, const char* label, const siz
 class Test_BigInt_Performance : public ::testing::Test
 {
 protected:
-    static constexpr size_t number_count = 2;
-    const std::vector<size_t> sizes = {10, 100, 1000, 10000, 50000};
+    static constexpr size_t number_count = 50;
+    const std::vector<size_t> sizes = {10, 100, 1000, 10000};
     volatile int dce_sink = 0;
 
     void SetUp() override {
@@ -356,7 +356,8 @@ INSTANTIATE_TEST_SUITE_P(LargeValueDiv, BigInt_DivParamTest, ::testing::Values(
                              TestCase{kHugeA, kHugeA, "1"},
                              TestCase{"0", kHugeA, "0"},
                              TestCase{kHugeA, "-" + std::string{kHugeB}, "-" + std::string{AdivB}},
-                             TestCase{kHugeB, kHugeA, "0"}
+                             TestCase{kHugeB, kHugeA, "0"},
+                             TestCase{"12345678901234567890", "4117416960", "2998403858"}
                          ));
 
 INSTANTIATE_TEST_SUITE_P(LargeValueMod, BigInt_ModParamTest, ::testing::Values(