Petya and Inequiations 题解

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Little Petya loves inequations. Help him find n positive integers a1, a2, ..., an, such that the following two conditions are satisfied:

  • a12 + a22 + ... + an2 ≥ x
  • a1 + a2 + ... + an ≤ y
Input

The first line contains three space-separated integers nx and y (1 ≤ n ≤ 105, 1 ≤ x ≤ 1012, 1 ≤ y ≤ 106).

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is recommended to use cin, cout streams or the %I64d specificator.

Output

Print n positive integers that satisfy the conditions, one integer per line. If such numbers do not exist, print a single number "-1". If there are several solutions, print any of them.

Example
Input
5 15 15
Output
44112
Input
2 3 2
Output
-1
Input
1 99 11
Output
11

思路:

a1 + a2 + ... + an= y,那么现在想办法如何拆分y使得a12 + a22 + ... + an2取得最大值,当其中n-1个数都取1,剩下一个数取y-(n-1)时a12 + a22 + ... + an2取得最大值。因此,令a1 + a2 + ... + an= y时,若a12 + a22 + ... + an2大于等于x,那么存在解,且此时的a1,…,an是其中的一组解,否则不存在解。

代码:

#include <iostream>using namespace std;int main(){    int64_t n,y;    int64_t x;    while(cin>>n>>x>>y)    {        if(y>=n)        {            int64_t temp=y-(n-1);            if(temp*temp+(n-1)>=x)            {                cout<<temp<<endl;                for(int i=0;i<n-1;i++)                    cout<<1<<endl;            }            else                cout<<-1<<endl;        }        else            cout<<-1<<endl;    }    return 0;}


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