今日SGU 5.29

sgu 299

题意：给你n个线段，然后问你能不能选出其中三个组成一个三角形，数字很大

收获：另一个大整数模板

#include<bits/stdc++.h>
#define de(x) cout<<#x<<"="<<x<<endl;
#define dd(x) cout<<#x<<"="<<x<<" ";
#define rep(i,a,b) for(int i=a;i<(b);++i)
#define repd(i,a,b) for(int i=a;i>=(b);--i)
#define repp(i,a,b,t) for(int i=a;i<(b);i+=t)
#define ll long long
#define mt(a,b) memset(a,b,sizeof(a))
#define fi first
#define se second
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
#define pii pair<int,int>
#define pdd pair<double,double>
#define pdi pair<double,int>
#define mp(u,v) make_pair(u,v)
#define sz(a) (int)a.size()
#define ull unsigned long long
#define ll long long
#define pb push_back
#define PI acos(-1.0)
#define qc std::ios::sync_with_stdio(false)
#define db double
#define all(a) a.begin(),a.end()
const int mod = 1e9+7;
const int maxn = 1e3+6;
const double eps = 1e-6;
using namespace std;
class bign
{
public:
    int len, s[maxn];//数的长度，记录数组
//构造函数
    bign();
    bign(const char*);
    bign(int);
    bool sign;//符号 1正数 0负数
    string toStr() const;//转化为字符串，主要是便于输出
    friend istream& operator>>(istream &,bign &);//重载输入流
    friend ostream& operator<<(ostream &,bign &);//重载输出流
//重载复制
    bign operator=(const char*);
    bign operator=(int);
    bign operator=(const string);
//重载各种比较
    bool operator>(const bign &) const;
    bool operator>=(const bign &) const;
    bool operator<(const bign &) const;
    bool operator<=(const bign &) const;
    bool operator==(const bign &) const;
    bool operator!=(const bign &) const;
//重载四则运算
    bign operator+(const bign &) const;
    bign operator++();
    bign operator++(int);
    bign operator+=(const bign&);
    bign operator-(const bign &) const;
    bign operator--();
    bign operator--(int);
    bign operator-=(const bign&);
    bign operator*(const bign &)const;
    bign operator*(const int num)const;
    bign operator*=(const bign&);
    bign operator/(const bign&)const;
    bign operator/=(const bign&);
//四则运算的衍生运算
    bign operator%(const bign&)const;//取模（余数）
    bign factorial()const;//阶乘
    bign Sqrt()const;//整数开根（向下取整）
    bign pow(const bign&)const;//次方
//一些乱乱的函数
    void clean();
    ~bign();
};
#define max(a,b) a>b ? a : b
#define min(a,b) a<b ? a : b  

bign::bign()
{
    memset(s, 0, sizeof(s));
    len = 1;
    sign = 1;
}  

bign::bign(const char *num)
{
    *this = num;
}  

bign::bign(int num)
{
    *this = num;
}  

string bign::toStr() const
{
    string res;
    res = "";
    for (int i = 0; i < len; i++)
        res = (char)(s[i] + ‘0‘) + res;
    if (res == "")
        res = "0";
    if (!sign&&res != "0")
        res = "-" + res;
    return res;
}  

istream &operator>>(istream &in, bign &num)
{
    string str;
    in>>str;
    num=str;
    return in;
}  

ostream &operator<<(ostream &out, bign &num)
{
    out<<num.toStr();
    return out;
}  

bign bign::operator=(const char *num)
{
    memset(s, 0, sizeof(s));
    char a[maxn] = "";
    if (num[0] != ‘-‘)
        strcpy(a, num);
    else
        for (int i = 1; i < strlen(num); i++)
            a[i - 1] = num[i];
    sign = !(num[0] == ‘-‘);
    len = strlen(a);
    for (int i = 0; i < strlen(a); i++)
        s[i] = a[len - i - 1] - 48;
    return *this;
}  

bign bign::operator=(int num)
{
    if (num < 0)
        sign = 0, num = -num;
    else
        sign = 1;
    char temp[maxn];
    sprintf(temp, "%d", num);
    *this = temp;
    return *this;
}  

bign bign::operator=(const string num)
{
    const char *tmp;
    tmp = num.c_str();
    *this = tmp;
    return *this;
}  

bool bign::operator<(const bign &num) const
{
    if (sign^num.sign)
        return num.sign;
    if (len != num.len)
        return len < num.len;
    for (int i = len - 1; i >= 0; i--)
        if (s[i] != num.s[i])
            return sign ? (s[i] < num.s[i]) : (!(s[i] < num.s[i]));
    return !sign;
}  

bool bign::operator>(const bign&num)const
{
    return num < *this;
}  

bool bign::operator<=(const bign&num)const
{
    return !(*this>num);
}  

bool bign::operator>=(const bign&num)const
{
    return !(*this<num);
}  

bool bign::operator!=(const bign&num)const
{
    return *this > num || *this < num;
}  

bool bign::operator==(const bign&num)const
{
    return !(num != *this);
}  

bign bign::operator+(const bign &num) const
{
    if (sign^num.sign)
    {
        bign tmp = sign ? num : *this;
        tmp.sign = 1;
        return sign ? *this - tmp : num - tmp;
    }
    bign result;
    result.len = 0;
    int temp = 0;
    for (int i = 0; temp || i < (max(len, num.len)); i++)
    {
        int t = s[i] + num.s[i] + temp;
        result.s[result.len++] = t % 10;
        temp = t / 10;
    }
    result.sign = sign;
    return result;
}  

bign bign::operator++()
{
    *this = *this + 1;
    return *this;
}  

bign bign::operator++(int)
{
    bign old = *this;
    ++(*this);
    return old;
}  

bign bign::operator+=(const bign &num)
{
    *this = *this + num;
    return *this;
}  

bign bign::operator-(const bign &num) const
{
    bign b=num,a=*this;
    if (!num.sign && !sign)
    {
        b.sign=1;
        a.sign=1;
        return b-a;
    }
    if (!b.sign)
    {
        b.sign=1;
        return a+b;
    }
    if (!a.sign)
    {
        a.sign=1;
        b=bign(0)-(a+b);
        return b;
    }
    if (a<b)
    {
        bign c=(b-a);
        c.sign=false;
        return c;
    }
    bign result;
    result.len = 0;
    for (int i = 0, g = 0; i < a.len; i++)
    {
        int x = a.s[i] - g;
        if (i < b.len) x -= b.s[i];
        if (x >= 0) g = 0;
        else
        {
            g = 1;
            x += 10;
        }
        result.s[result.len++] = x;
    }
    result.clean();
    return result;
}  

bign bign::operator * (const bign &num)const
{
    bign result;
    result.len = len + num.len;  

    for (int i = 0; i < len; i++)
        for (int j = 0; j < num.len; j++)
            result.s[i + j] += s[i] * num.s[j];  

    for (int i = 0; i < result.len; i++)
    {
        result.s[i + 1] += result.s[i] / 10;
        result.s[i] %= 10;
    }
    result.clean();
    result.sign = !(sign^num.sign);
    return result;
}
bign bign::operator*(const int num)const
{
    bign x = num;
    bign z = *this;
    return x*z;
}
void bign::clean()
{
    if (len == 0) len++;
    while (len > 1 && s[len - 1] == ‘\0‘)
        len--;
}
bign::~bign()
{
}
bign a[maxn];
int main(){
    int n;
    scanf("%d",&n);
    rep(i,1,n+1) cin>>a[i];
    sort(a+1,a+n+1);
    rep(i,3,n+1) if(a[i] < a[i-1] + a[i-2]) {
        cout<<a[i]<<" "<<a[i-1]<<" "<<a[i-2]<<endl;
        return 0;
    }
    puts("0 0 0");
    return 0;
}

原文地址：https://www.cnblogs.com/chinacwj/p/9107414.html