primitive_types.cpp

#include <random>
#include<bits/stdc++.h>
using namespace std;

// https://leetcode.com/problems/rectangle-area/submissions/
int computeArea(int A, int B, int C, int D, int E, int F, int G, int H) {
        int x1 = max(A, E);
        int x2 = min(C, G);
        int y1 = max(B, F);
        int y2 = min(D, H);

        int area = (x2-x1) * (y2-y1);
        if(x1 > x2 || y1 > y2) area = 0;
        return (C-A) * (D-B) - area + (G-E) * (H-F);
    }

// https://leetcode.com/problems/rectangle-overlap/submissions/
bool isRectangleOverlap(vector<int>& rec1, vector<int>& rec2) {
        int x1 = max(rec1[0], rec2[0]);
        int x2 = min(rec1[2], rec2[2]);
        int y1 = max(rec1[1], rec2[1]);
        int y2 = min(rec1[3], rec2[3]);

        return x1 < x2 && y1 < y2;
    }


bool isPalindrome(int x) {
        if(x < 0) return false;
        if(x == 0) return true;

        int nOfDigits = floor(log10(x));
        int top = 1;
        while(nOfDigits--) top *= 10;
        while(x) {
            if(x / top != x % 10) return false;
            x = x % top / 10;
            top /= 100;
        }
        return true;
    }

// using folding
short parity(unsigned long long x) {
    for(int i = 5; i >= 0; --i) x ^= (x >> (1 << i));
    return x &= 1;
}



unsigned long long add(unsigned long long a, unsigned long long b) {
    unsigned long long sum = 0, carryin = 0, k = 1, temp_a = a, temp_b = b;
    while(temp_a || temp_b) {
        int ak = a & k, bk = b & k;
        unsigned long long carryout = (ak & bk) | (ak & carryin) | (bk & carryin);
        sum |= (ak ^ bk ^ carryin);
        carryin = carryout << 1, temp_a >>= 1, temp_b >>= 1, k <<= 1;
    }
    return sum | carryin;
}

unsigned long long multiply(unsigned long long x, unsigned long long y) {
    unsigned long long sum = 0;
    while(x) {
        if(x & 0x1) sum = add(sum, y);
        x >>= 1, y <<= 1;
    }
    return sum;
}

int concatNum(int d, int n) {
    int ret = 0;
    while(n) { ret *= 10, ret += d, --n;  }
    return ret;
}

bool checkConcatenatedSum(int num, int catlen) {
    int tmpNum = num;
    int sum = 0;
    cout << num << endl;
    while(tmpNum) {
        sum += concatNum(tmpNum % 10, catlen), tmpNum /= 10;
        cout << sum << endl;
    }
    cout << endl;
    return sum == num;
}

void test() {
//    cout << numeric_limits<float>::max() << endl;
//    cout << numeric_limits<float>::min() << endl;
//    default_random_engine engine;
//    uniform_int_distribution<int> dist(1,6);
//    cout << dist(engine) << endl;
//    cout << dist(engine) << endl;
//    cout << dist(engine) << endl;
//    cout << dist(engine) << endl;
//
//    uniform_int_distribution<unsigned long long> dist2(numeric_limits<unsigned long long>::min(), numeric_limits<unsigned long long>::max());
//    cout << dist2(engine) << endl;
//    cout << parity(4) << endl;
//    cout << parity(5) << endl;

    cout << multiply(10, 11) << endl;
    cout << checkConcatenatedSum(198, 2) << endl;
    cout << checkConcatenatedSum(2997, 3) << endl;
    cout << checkConcatenatedSum(198, 3) << endl;
    cout << checkConcatenatedSum(13332, 4) << endl;
    cout << checkConcatenatedSum(9, 1) << endl;
}

class SolutionReverseInteger {
public:
    int reverse(int x) {
        bool neg = false;
        if(neg) x *= -1, neg = true;
        
        long long ret = 0;
        
        while(x) {    
            ret = ret * 10 + x % 10;
            x /= 10;
        }
        
        ret = (neg ? -1 : 1) * ret;
        
        if(ret < numeric_limits<int>::min() || ret > numeric_limits<int>::max()) return 0;
        
        return ret;
    }
};

int main() {
    test();
}