Problems: Variables and Types

Kenji is testing the input box of a new tool. He wants the smallest possible program that proves a number went in and came out again.

Input. One line with one integer n.

Output. One line: the number, one space, then the word stored.

Constraints. -1000000 <= n <= 1000000.

Sample. Input 42 gives 42 stored.

#include <stdio.h>

int main(void)
{
    int n = 0;
    scanf("%d", &n);

    /* One printf. Nothing else. */

    return 0;
}

Bob is sorting two boxes of books and the labels are on the wrong boxes. Swap them, using a third variable to park the first value.

Input. One line with two integers a b.

Output. One line with the two numbers in the other order, separated by exactly one space.

Constraints. -1000000 <= a, b <= 1000000.

Sample. Input 10 20 gives 20 10.

#include <stdio.h>

int main(void)
{
    int a = 0;
    int b = 0;
    int spare = 0;
    scanf("%d %d", &a, &b);

    /* Three assignments, then one printf. */

    return 0;
}

Amara adds up two readings from a sensor. Each reading fits in an int, and their sum does not.

Input. One line with two integers a b.

Output. One line with their sum.

Constraints. 0 <= a, b <= 2000000000.

Sample. Input 2000000000 2000000000 gives 4000000000.

#include <stdio.h>

int main(void)
{
    int a = 0;
    int b = 0;
    scanf("%d %d", &a, &b);

    /* The inputs fit in an int. The answer does not. */

    return 0;
}

Zara is cutting circular table mats and needs the area of each one, to two decimal places.

Input. One line with one decimal number r, the radius in centimetres.

Output. One line with the area, to exactly two decimal places.

Constraints. 0.01 <= r <= 1000.00. Use 3.14159265358979 for pi.

Sample. Input 2.5 gives 19.63.

#include <stdio.h>

int main(void)
{
    double r = 0.0;
    scanf("%lf", &r);

    /* One printf, with %.2f. */

    return 0;
}

A server has been running for a very large number of seconds. Zara wants that written out as days, hours, minutes and seconds.

Input. One line with one integer s, the number of seconds.

Output. One line: d days, h hours, m minutes, s seconds, with the four numbers filled in.

Constraints. 0 <= s <= 1000000000000. The words are not adjusted for 1; print them exactly as shown.

Sample. Input 90061 gives 1 days, 1 hours, 1 minutes, 1 seconds.

#include <stdio.h>

int main(void)
{
    long long s = 0;
    scanf("%lld", &s);

    /* 86400 seconds in a day, 3600 in an hour, 60 in a minute. */

    return 0;
}

Kenji's desk lamp starts off. Somebody flips the switch n times. Say whether the lamp is on at the end.

Input. One line with one integer n, the number of flips.

Output. One line: 1 if the lamp is on, otherwise 0.

Constraints. 0 <= n <= 1000000000. No loop is needed, and none is wanted.

Sample. Input 7 gives 1. Input 0 gives 0.

#include <stdio.h>

int main(void)
{
    int n = 0;
    scanf("%d", &n);

    /* No loop. What is left over when n is divided by 2? */

    return 0;
}

Amara is working out how much memory a table of readings will need, before she asks for it.

Input. One line with one integer n, the number of readings.

Output. One line with the number of bytes that n values of type double would take.

Constraints. 0 <= n <= 1000000000. Take the size from sizeof, never from a number you typed.

Sample. Input 10 gives 80.

#include <stdio.h>

int main(void)
{
    long long n = 0;
    scanf("%lld", &n);

    /* Multiply by sizeof(double), print with %lld. */

    return 0;
}

Maria's shop keeps its ledger in paisa, never in taka, because whole numbers never drift. One day's row has an opening balance, one deposit and one withdrawal.

Input. One line with three integers: the opening balance, the deposit and the withdrawal, all in paisa.

Output. One line with the closing balance written as taka: the whole taka, a full stop, then exactly two digits of paisa.

Constraints. 0 <= opening, deposit <= 1000000000000000, and the withdrawal never takes the balance below zero. No double anywhere.

Sample. Input 100000 25050 5000 gives 1200.50.

#include <stdio.h>

int main(void)
{
    long long opening = 0;
    long long deposit = 0;
    long long withdrawal = 0;
    scanf("%lld %lld %lld", &opening, &deposit, &withdrawal);

    /* Do every sum in paisa. Put the decimal point back only when you print. */

    return 0;
}

Zara is checking a column of totals. She wants to know whether the first two numbers add up to the third, without being fooled by the last decimal place.

Input. One line with three decimal numbers a b c.

Output. One line: 1 if a + b is within 0.000000001 of c, otherwise 0.

Constraints. -1000000 <= a, b, c <= 1000000. One hidden test is 0.1 0.2 0.3, and the answer there is 1.

Sample. Input 0.1 0.2 0.3 gives 1. Input 1.0 1.0 3.0 gives 0.

#include <stdio.h>
#include <math.h>

int main(void)
{
    double a = 0.0;
    double b = 0.0;
    double c = 0.0;
    scanf("%lf %lf %lf", &a, &b, &c);

    /* One printf with %d. A comparison is already a 1 or a 0. */

    return 0;
}

Zara is designing a column in a file format. She needs the narrowest signed fixed-width type that holds every value the column may carry.

Input. One line with two integers lo hi, the smallest and the largest value the column may hold.

Output. One line with a width in bits: 8, 16, 32 or 64.

Constraints. -9000000000000000000 <= lo <= hi <= 9000000000000000000. No condition and no loop are needed.

Sample. Input -200 300 gives 16. Input 0 5000000000 gives 64.

#include <stdio.h>

int main(void)
{
    long long lo = 0;
    long long hi = 0;
    scanf("%lld %lld", &lo, &hi);

    /* Lesson 4: a comparison is a 1 or a 0, and two of them multiplied is "both". */

    return 0;
}