CareerCup

Using bitwise OR:

public int rand75(){
	return rand50() | rand50();
}

Generic pseudo-code, not intended to compile. Not tested, but I think it should work.

function int myRandom() {
    int roll1 = originalRandom();
    int roll2 = originalRandom();

    // Only 4 possible combinations, with equal probabilities:
    // roll1 = roll2 = 0
    // roll1 = roll2 = 1
    // roll1 = 0; roll2 = 1
    // roll1 = 1; roll2 = 0

    if (roll1 == 0 && roll2 == 0)  // 25% probability
        return 0;
    else  // 75% probability
        return 1;
}

Considering rand50() is defined, then rand75() would be

char rand75() {
    return !(rand50() && rand50());
}

#include <stdlib.h>     /* srand, rand */
#include <time.h>       /* time */

int rand50(){
    srand(time(NULL));
    int randInt= rand(); // randInt is between 0 and RAND_MAX
    (x%2)==0? return 1 : return 0;
}

int rand75(){
    int x = rand50();   // x is now one of {0, 1}
    x = x << 1;           // x is now one of {00, 10}
    x = x ^ rand50();  // x is now one of {00, 01, 10, 11} in binaries
    (x>0)? return 1 : return 0;
}

Pretty rusty with probabilities, so let me know your thoughts if this works out to be 75%
My first test, I rolled 12 times, got 9 rolls that returned 1, 3 rolls that return 0, gave me exactly: 9/12 = 75%
Sample size should be larger, so I should run more tests.

/* The lowest number of rolls to get a combination of 4 such that we can pick 3 out of 4
to give the 75% probability is through two rolls:

Roll Results
1: 0, 0
2: 0, 1
3: 1, 0
4: 1, 1

Pick 1 - 3 to return 1 for 75%
Pick 4 to return 0 for 25% probability
*/

#include <stdlib.h>
#include <time.h>
#include <iostream>

using namespace std;

int random50()
{
	int result = rand() % 2;
	return result;
}

int random75()
{
	const int size = 3;
	int valuesFor1[size] = { 0, 1, 10 };
	
	// First roll is for the 10's digit place
	int roll1 = random50();
	int roll2 = random50();
	int result = (roll1 * 10) + roll2;
	for (int i = 0; i < size; ++i) 
	{
		if (result == valuesFor1[i])
		{
			return 1;
		}
	}
	return 0;
}

int main() 
{
	srand (time(NULL));
	int value = random75();
	cout << value << endl;
	return 0;
}

Generic pseudo-code, not intended to compile. Not tested, but I think it should work.

function int myRandom() {
    int roll1 = originalRandom();
    int roll2 = originalRandom();

    // Only 4 possible combinations, with equal probabilities:
    // roll1 = roll2 = 0
    // roll1 = roll2 = 1
    // roll1 = 0; roll2 = 1
    // roll1 = 1; roll2 = 0

    if (roll1 == 0 && roll2 == 0)  // 25% probability
        return 0;
    else  // 75% probability
        return 1;
}

Generic pseudo-code, not intended to compile. Not tested, but I think it should work.

function int myRandom() {
    int roll1 = originalRandom();
    int roll2 = originalRandom();

    // Only 4 possible combinations, with equal probabilities:
    // roll1 = roll2 = 0
    // roll1 = roll2 = 1
    // roll1 = 0; roll2 = 1
    // roll1 = 1; roll2 = 0

    if (roll1 == 0 && roll2 == 0)  // 25% probability
        return 0;
    else  // 75% probability
        return 1;
}

bool rand75(){
if(rand50()==1)
return1;
return rand50();
}

from random import randint

# given function
def rand_50() :
    return randint(0,1)

# requested function
def rand_75() :
    if (rand_50() + rand_50()) == 2 :
        return 0
    else :
        return 1

# test distribution over n outcomes
def test(n) :
    outcome = 0
    for i in range(0,n) :
        outcome = outcome + rand_75()
    p_1 = outcome / n
    p_0 = 1 - p_1
    print("p_0= %s, p_1= %s " % (p_0, p_1))

test(10000)

import random


def rand_0_5():
    return 1 if random.random() >= 0.5 else 0


def rand_0_75():
    return 0 if not (rand_0_5() + rand_0_5()) else 1

public int random75(){
	int ans = random50(); // 50%
	if(ans == 0){
		ans = random50();   //for 0 50% / 2 = 25%
	}
	return ans;
}