Codeforces Round #196 (Div. 2) 少部分题解

A:sort以后求差值最小

int a[];
int main()
{
    int n,m;
    cin>>n>>m;
    for(int i =  ; i < m ; i++) cin>>a[i];
    sort(a,a+m);
    int mm = INF;
    for(int i =  ; i+n- < m ; i++)
        mm = min(mm,a[i+n-]-a[i]);
    cout<<mm<<endl;
    return ;
}

B:求屏幕黑框占屏幕的几分之几 . 求LCM后的差值

LL gcd(LL a,LL b){ return b?gcd(b,a%b):a; }
LL lcm(LL a,LL b){ return a*b/gcd(a,b); }
int main()
{
    LL a,b,c,d;
    LL a1,b1,c1,d1;
    cin>>a>>b>>c>>d;
    a1 = a;
    b1 = b;
    c1 = c;
    d1 = d;
    LL p = lcm(a,c);
    b = b * (p/a);
    a = p;
    d = d * (p/c);
    c = p;
    if(b > d) {
        LL x = b-d;
        LL y = b;
        printf("%I64d/%I64d\n",x/gcd(x,y),y/gcd(x,y));
        return ;
    }else if(b == d) printf("0/1\n");

    LL q = lcm(b1,d1);
    a1 = a1 * (q/b1);
    b1 = q;
    c1 = c1 * (q/d1);
    d1 = q;
    if(a1 > c1){
        LL x = a1-c1;
        LL y = a1;
        printf("%I64d/%I64d\n",x/gcd(x,y),y/gcd(x,y));
        return ;
    }

    return ;
}