1模拟卷12CSP-J入门级第一轮认证模拟卷12

程序1

```cpp

include <iostream>

using namespace std;

int main() {

    int n, sum = 0;

    cin >> n;

    while (n) {

        sum += n % 10;

        n /= 10;

    }

    cout << sum;

    return 0;

}

```

程序2

```cpp

include <iostream>

using namespace std;

int main() {

    int a, b;

    cin >> a >> b;

    int c = a ^ b;

    a = a ^ c;

    b = b ^ c;

    cout << a << " " << b;

    return 0;

}

```

程序3

```cpp

include <iostream>

using namespace std;

int f(int n) {

    if (n <= 1) return n;

    return f(n-1) + f(n-2);

}

int main() {

    int n;

    cin >> n;

    cout << f(n);

    return 0;

}

```

程序1（判断质数）

```cpp

include <iostream>

include <cmath>

using namespace std;

bool isPrime(int n) {

    if (n <= 1) return false;

    for (int i = 2; i <= ______; i++) { // 31

        if (n % i == 0) return false;

    }

    return true;

}

int main() {

    int n;

    cin >> n;

    cout << (isPrime(n) ? "Yes" : "No");

    return 0;

}

```

程序2（选择排序）

```cpp

include <iostream>

using namespace std;

int main() {

    int n, a[100];

    cin >> n;

    for (int i=0; i<n; i++) cin >> a[i];

    for (int i=0; i<n-1; i++) {

        int min_idx = i;

        for (int j=i+1; j<n; j++) {

            if (a[j] < a[min_idx]) ______; // 32

        }

        swap(a[i], a[min_idx]);

    }

    // 输出略

    return 0;

}

```

程序3（二分查找）

```cpp

include <iostream>

using namespace std;

int binarySearch(int arr[], int l, int r, int x) {

    while (l <= r) {

        int mid = l + (r - l) / 2;

        if (arr[mid] == x) return mid;

        if (arr[mid] < x) l = mid + 1;

        else ______; // 33

    }

    return -1;

}

// 主函数略

```