Informatics Olympiad 1.3: The control structure of the program (1)

The first part of C++ language

Chapter III Program Control Structure

The first section if selection structure

1039 Judgment number is positive or negative

​#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    if (n > 0) {
        cout << "positive" << endl;
    }
    else if (n == 0) {
        cout << "zero" << endl;
    }
    else {
        cout << "negative" << endl;
    }

    return 0;
}

1040 Output absolute value

#include <cstdio>
using namespace std;

int main() {
    float a;
    scanf("%f",&a);

    if (a < 0) {
        printf("%.2f\n", -1 * a);
    }
    else {
        printf("%.2f\n", a);
    }

    return 0;
}

1041 Parity Judgment

#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    if (n%2 == 0) {
        cout << "even" << endl;
    }
    else {
        cout << "odd" << endl;
    }

    return 0;
}

1042 Parity ASCII value judgment

#include <iostream>
using namespace std;

int main() {
    char c;
    cin >> c;

    if (c%2 == 1) {
        cout << "YES" << endl;
    }
    else {
        cout << "NO" << endl;
    }

    return 0;
}

1043 integer size comparison

#include <iostream>
using namespace std;

int main() {
    int x, y;
    cin >> x >> y;

    if (x > y) {
        cout << '>' << endl;
    }
    else if (x == y) {
        cout << '='<< endl;
    }
    else {
        cout << '<' << endl;
    }

    return 0;
}

1044 Determine whether it is a two-digit number

#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    if (n >=10 && n <= 99) {
        cout << 1 << endl;
    }
    else {
        cout << 0 << endl;
    }

    return 0;
}

1045 Collect bottle caps to win big prizes

#include <iostream>
using namespace std;

int main() {
    int a, b;
    cin >> a >> b;

    if (a>=10 || b >=20) {
        cout << 1 << endl;
    }
    else {
        cout << 0 << endl;
    }

    return 0;
}

1046 Determine whether a number is divisible by 3 and 5 at the same time

#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    if (n%3 == 0 && n%5 ==0) {
        cout << "YES" << endl;
}
    else {
        cout << "NO" << endl;
    }

    return 0;
}

1047 Determine whether it can be divisible by 3, 5, 7

#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    if (n%3!=0 && n%5!=0 && n%7!=0) {
        cout << 'n' << endl;
    }
    else {
        if (n%3 == 0) {
            cout << "3 ";
        }
        if (n%5 == 0) {
            cout << "5 ";
        }
        if (n%7 == 0) {
            cout << "7 ";
        }
    }

    return 0;
}

1048 A student who failed a course

#include <iostream>
using namespace std;

int main() {
    int a, b;
    cin >> a >> b;

    if ((a>=60) == (b>=60)) {
        cout << 0 << endl;
    }
    else {
        cout << 1 << endl;
    }

    return 0;
}

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