palindrome.cc

palindrome.cc

#include "iostream"
#include "cstdint"
#include "chrono"

// Mac M1 (Apple clang version 13.0.0) 2.9s
//    - Highest palindrome -> 98344389
// Ryzen 5 3600x (MinGW-W64 8.1.0) 1.6s
//    - Highest palindrome -> 98344389

uint16_t intLen(uint64_t forInt) {

    uint64_t factor = 1;
    uint16_t intLen;

    for ( intLen = 0 ; (forInt / factor) != 0 ; intLen++ ) {
        factor *= 10;
    }

    return intLen;
}

uint64_t intReverse(uint64_t forInt) {

    uint8_t factor = 1;
    uint64_t res = 0;

    for ( uint16_t it = 0 ; forInt != 0 ;  it++ ) {
        res = (res * factor) + (forInt % 10);
        forInt = forInt / 10;
        if ( it == 0 )
            factor = 10;
    }
    return res;
}
    
int32_t main(int32_t argc, char const *argv[]) {
    std::chrono::time_point start = std::chrono::high_resolution_clock::now();
    uint64_t highest = 0;
    uint64_t res = 0;
    for (uint16_t loop = 1000; loop != 9999 ; ++loop) {
        for (uint16_t loopy = 1000; loopy != 9999 ; ++loopy) {
            res = loop*loopy;
            if ( intReverse(res) == res && res > highest )
                highest = res;
        }
    }
  
    std::chrono::time_point stop = std::chrono::high_resolution_clock::now();
    float duration = ((float)(std::chrono::duration_cast<std::chrono::milliseconds>(stop - start).count())) / 1000.0f;
    std::cout << "Highest palindrome -> " << highest << std::endl;
    std::cout << "Found in -> " << duration << std::endl;
    return 0;
}