求各位教教我，这是俺们任务🥺

2.

#include <iostream>
using namespace std;
int main()
{
    double a,b,c;
    cin >>a>>b>>c;
    if(a+b>c && a+c >b && b+c>a)
        cout << "It is triangle"<<endl;
    else
        cout << "It isn't triangel" << endl;
    return 0;
}

3.

#include <iostream>
using namespace std;
int main()
{
    int n,nmb = 0,i;
    int buf[6]={0};
    cin >> n;
    while(n)
    {
        buf[i]=n%10;
        nmb++;
        n/=10;
    }
    cout << nmb << endl;
    for(i=nmb-1; i>=0;i--)
        cout << buf[i];
    cout << endl;
    for(i=0;i<nmb;i++)
        cout << buf[i];
    cout << endl;
    return 0;
}

#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
    /***** 判断三角形   ******/
    int a[3];
    cin>>a[0]>>a[1]>>a[2];
    sort(a,a+3);
    if(a[0] + a[1] <= a[2] && a[2] - a[1] >= a[0])
    {
        cout<<"it isn’t triangle";
    }else {
        cout<<"it is triangle";
    }
    cout<<endl;
    
    /******* 下一题 ********/ 
    int num,b[5] = {0};
    cin>>num;
    int cnt  = 4,count = 0;
    while(1)
    {
        if(!num) break;
        count++;
        b[cnt--] = num % 10;
        num /= 10;
    }
    cout<<count<<endl;
    for(int i = cnt+1;i<5;i++)
    {
        cout<<b[i];
    }
    cout<<endl;
    for(int i = 4;i>cnt;i--)
    {
        cout<<b[i];
    }
    cout<<endl;
    
    
    return 0;
}