poj2100

  题目给出一个数，求一个连续序列使得它们的平方和等于这个数

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
#define pii pair<int,int>
#define ll long long
vector<pii>v;
bool cmp(pii a,pii b)
{
    return (a.second-a.first+1)>(b.second-b.first+1);
}
int main()
{
    v.clear();
    ll n,low=1,up,sum=0;
    cin>>n;
    for(up=1;up*up<=n;up++)
    {
        sum+=up*up;
        if(sum==n)
        {
            v.push_back(make_pair(low,up));
        }
        while(low<up&&sum>=n)
        {
            sum-=low*low;
            low++;
            if(sum==n)
            {
                v.push_back(make_pair(low,up));
            }

        }
    }
    sort(v.begin(),v.end(),cmp);
    int sz=v.size();
    cout<<sz<<endl;
    for(int i=0;i<sz;i++)
    {
        cout<<v[i].second-v[i].first+1<<" ";
        for(int j=v[i].first;j<=v[i].second;j++)
            cout<<j<<" ";
        cout<<endl;
    }
    return 0;
}