21年

45题

#include <stdio.h>

#define N 1010

int arr[N];

// 选择排序
void sort(int *arr, int len) {
    for (int i = 0; i < len - 1; i++) {
        int m = i;
        for (int j = i + 1; j < len; j++) {
            if (arr[j] < arr[m]) m = j;
        }
        int t = arr[i];
        arr[i] = arr[m];
        arr[m] = t;
    }
}

int main() {
    int x, y;
    scanf("%d%d", &x, &y);
    int pa = 0;
    while (x) {
        arr[pa++] = x % 10;
        x /= 10;
    }
    while (y) {
        arr[pa++] = y % 10;
        y /= 10;
    }
    sort(arr, pa);
    for (int i = pa - 1; i >= 0; i--) printf("%d", arr[i]);
    return 0;
}

46题

#include <stdio.h>

#define N 1010

int arr[N];

// 选择排序
void sort(int *arr, int len) {
    for (int i = 0; i < len - 1; i++) {
        int m = i;
        for (int j = i + 1; j < len; j++) {
            if (arr[j] < arr[m]) m = j;
        }
        int t = arr[i];
        arr[i] = arr[m];
        arr[m] = t;
    }
}

int main() {
    int x, y;
    scanf("%d%d", &x, &y);
    int pa = 0;
    while (x) {
        arr[pa++] = x % 10;
        x /= 10;
    }
    while (y) {
        arr[pa++] = y % 10;
        y /= 10;
    }
    sort(arr, pa);
    for (int i = 0; i < pa; i++) printf("%d", arr[i]);
    return 0;
}

47题

#include <stdio.h>

#define N 1010

int arr[N];

// 选择排序
void sort(int *arr, int len) {
    for (int i = 0; i < len - 1; i++) {
        int m = i;
        for (int j = i + 1; j < len; j++) {
            if (arr[j] < arr[m]) m = j;
        }
        int t = arr[i];
        arr[i] = arr[m];
        arr[m] = t;
    }
}

int main() {
    int x, y;
    scanf("%d%d", &x, &y);
    int pa = 0;
    while (x) {
        arr[pa++] = x % 10;
        x /= 10;
    }
    while (y) {
        arr[pa++] = y % 10;
        y /= 10;
    }
    sort(arr, pa);
    if (!arr[0]) {
        for (int i = 1; i < pa; i++) {
            if (arr[i]) {
                int t = arr[0];
                arr[0] = arr[i];
                arr[i] = t;
                break;
            }
        }
        for (int i = 0; i < pa; i++) printf("%d", arr[i]);
    }
    else {
        for (int i = 0; i < pa; i++) printf("%d", arr[i]);
    }
    return 0;
}

48题

#include <stdio.h>

int res;

int condition1(int x) {
    if (x == 1) return 0;
    int cnt = 0;
    for (int i = 2; i * i <= x; i++) {
        if (x % i == 0) cnt++;
    }
    if (cnt) return 0;
    return 1;
}

int condition2(int x) {
    if (x < 10) return 1;
    int arr[10010], cnt = 0;
    while (x) {
        arr[cnt++] = x % 10;
        x /= 10;
    }
    int flag = 1;
    for (int i = 0; i < cnt / 2; i++) {
        if (arr[i] != arr[cnt - 1 - i]) {
            flag = 0;
            break;
        }
    }
    if (flag) return 1;
    return 0;
}

int condition3(int x) {
    int sum = 0;
    while (x) {
        sum += x % 10;
        x /= 10;
    }
    if (sum % 7) return 0;
    return 1;
}

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

    for (int i = 2; i <= n; i++) {
        if (condition1(i) && condition2(i) && condition3(i)) {
            res++;
            // printf("%d ", i);
        }
    }
    // printf("\n");
    printf("%d\n", res);
    return 0;
}