浙大PAT甲级-1029

寻找两条序列的中位数

一开始直接用库里的sort好像超时

最后改为并归排序（复杂度只有n）

#include <iostream>
#include <cstdio>
#include <vector>

using namespace std;
int n1,n2;

int main()
{
    int i;
    long x;
    cin>>n1;
    vector<long> seqa;
    for(i=0;i<n1;i++){
        scanf("%ld", &x);
        seqa.push_back(x);
    }

    cin>>n2;
    vector<long> seqb;
    for(i=0;i<n2;i++){
        scanf("%ld", &x);
        seqb.push_back(x);
    }

    vector<long> seq;
    int j=0;
    i=0;
    while(i<n1&&j<n2)
        if(seqa[i]>=seqb[j]){
            seq.push_back(seqb[j]);
            j++;
        }else if(seqa[i]<seqb[j]){
            seq.push_back(seqa[i]);
            i++;
        }

    if(i==n1){
        for(;j<n2;j++)
            seq.push_back(seqb[j]);
    }else if(j==n2){
        for(;i<n1;i++)
            seq.push_back(seqa[i]);
    }

    cout<<seq[(n1+n2-1)/2]<<endl;
    return 0;
}