• 1 枚举问题_例题
  • 1.1 abc问题
  • 1.2 反序数
  • 1.3 对称平方数1
• 2 枚举问题_习题
  • 2.1 与7无关的数
  • 2.2 百鸡问题

1 枚举问题_例题

1.1 abc问题

#include <cstdio>
int main() {
    int a, b, c;
    for (int a = 0; a <= 9; ++a) {
        for (int b = 0; b <= 9; ++b) {
            for (int c = 0; c <= 9; ++c) {
                if(100*a+10*b+c + 100*b+11*c == 532){
                    printf("%d %d %d\n", a, b, c);
                }
            }
        }
    }
    return 0;
}

1.2 反序数

#include <cstdio>
int Reverse(int x){
    int revx = 0;
    while(x != 0){
        revx *= 10;
        revx += x%10;
        x /= 10;
    }
    return revx;
}
int main() {
    for (int i = 1000; i <= 9999; ++i) {
        if(i * 9 == Reverse(i)){
            printf("%d\n", i);
        }
    }
    return 0;
}

1.3 对称平方数1

#include <cstdio>
int Reverse(int x){
    int revx = 0;
    while(x != 0){
        revx *= 10;
        revx += x%10;
        x /= 10;
    }
    return revx;
}
int main() {
    for (int i = 0; i <= 256; ++i) {
        if(i * i == Reverse(i * i)){
            printf("%d\n", i);
        }
    }
    return 0;
}

2 枚举问题_习题

2.1 与7无关的数

#include <cstdio>
int main() {
    int n, sum=0;
    scanf("%d", &n);
    for (int i = 1; i <= n; ++i) {
        if(i%7 == 0 || i/10 == 7 || i%10 == 7){
            continue;
        }
        sum += i*i;
    }
    printf("%d", sum);
    return 0;
}

2.2 百鸡问题