hdu 6168 Numbers

Numbers

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 514    Accepted Submission(s): 270

Problem Description

zk has n numbers a1,a2,...,an. For each (i,j) satisfying 1≤i<j≤n, zk generates a new number (ai+aj). These new numbers could make up a new sequence b1，b2,...,bn(n−1)/2.
LsF wants to make some trouble. While zk is sleeping, Lsf mixed up sequence a and b with random order so that zk can't figure out which numbers were in a or b. "I'm angry!", says zk.
Can you help zk find out which n numbers were originally in a?

 

Input

Multiple test cases(not exceed 10).
For each test case:
∙The first line is an integer m(0≤m≤125250), indicating the total length of a and b. It's guaranteed m can be formed as n(n+1)/2.
∙The second line contains m numbers, indicating the mixed sequence of a and b.
Each ai is in [1,10^9]

 

Output

For each test case, output two lines.
The first line is an integer n, indicating the length of sequence a;
The second line should contain n space-seprated integers a1,a2,...,an(a1≤a2≤...≤an). These are numbers in sequence a.
It's guaranteed that there is only one solution for each case.

 

题意 已经有an个数 对于 1≤i<j≤n，an中的数 两两相加，得到b数组  然后把a，b数组乱序  让你挑选出a数组的内容

 

#include<bits/stdc++.h>
using namespace std;
const int maxn = +;
map<int,int>mp;
int s[maxn];//记录a和b
int t[maxn];//存储a数组的结果
 
void init()
{
    mp.clear();
    memset(t,,sizeof(t));
}
 
int main()
{
    int n;
    while(~scanf("%d",&n) )
    {
        init();
        for(int i=;i<=n;i++)
            scanf("%d",&s[i]);
        sort(s+,s+n+);
        int tot = ;
        for(int i=;i<=n;i++)
        {
            if(tot + (tot-)*tot/ >= n)//总数够了  就不需要再选下去了
                break;
            int x= s[i];
            if(mp[x]== || mp.count(x)==)//前面是这个数在mp中 且数值为1 另外一个是这个不在mp中
            {
                for(int j=;j<tot;j++)
                {
                    mp[x+t[j]]++;//把新挑出来的数和之前的都相加
                }
                t[tot++] = x;//存储这个数
            }
            else
            {
                mp[x]--;//这个数之前出现过  所以不需要加了
            }
        }
        cout<<tot<<endl;
        for(int i=;i<tot;i++)
        {
            if(i)
                cout<<" ";
            cout<<t[i];
        }
        cout<<endl;
    }
    return ;
}