1089. Insert or Merge (25)

1. Insert or Merge (25)
   时间限制
   200 ms
   内存限制
   65536 kB
   代码长度限制
   16000 B
   判题程序
   Standard
   作者
   CHEN, Yue

According to Wikipedia:

Insertion sort iterates, consuming one input element each repetition, and growing a sorted output list. Each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list, and inserts it there. It repeats until no input elements remain.

Merge sort works as follows: Divide the unsorted list into N sublists, each containing 1 element (a list of 1 element is considered sorted). Then repeatedly merge two adjacent sublists to produce new sorted sublists until there is only 1 sublist remaining.

Now given the initial sequence of integers, together with a sequence which is a result of several iterations of some sorting method, can you tell which sorting method we are using?

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (<=100). Then in the next line, N integers are given as the initial sequence. The last line contains the partially sorted sequence of the N numbers. It is assumed that the target sequence is always ascending. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print in the first line either “Insertion Sort” or “Merge Sort” to indicate the method used to obtain the partial result. Then run this method for one more iteration and output in the second line the resulting sequence. It is guaranteed that the answer is unique for each test case. All the numbers in a line must be separated by a space, and there must be no extra space at the end of the line.
Sample Input 1:

10
3 1 2 8 7 5 9 4 6 0
1 2 3 7 8 5 9 4 6 0

Sample Output 1:

Insertion Sort
1 2 3 5 7 8 9 4 6 0

Sample Input 2:

10
3 1 2 8 7 5 9 4 0 6
1 3 2 8 5 7 4 9 0 6

Sample Output 2:

Merge Sort
1 2 3 8 4 5 7 9 0 6

这题有个坑点，就是它要求确认是哪个排序后，再进行一次排序，但是一次排序后的结果可能和原先一致，这种情况必须接着排，一直到不一致为之。
通过这题，加深了对于直接排序和归并排序的理解，我原先写的归并排序似乎有点问题，调了半天都不行。
还有伪插入排序，也值得借鉴。
另外，虽然sort引用vector的排序时，有两种调用方式，不知道为何有种会出错，只能先记住正确的方法。

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int n;
vector<int> result;
bool cmp(int a,int b);
bool merge(vector <int> a);
bool insert(vector <int> a);
bool check(vector <int> a,vector <int> b)
{
    for(int i=0;i<a.size();i++)
    {
        if(a[i]!=b[i])
            return false;
    }
    return true;
}

int main()
{
    freopen("in.txt","r",stdin);
    cin>>n;
    int x;
    vector<int> begin(n);
    for(int i=0;i<n;i++)
    {
        cin>>begin[i];
    }
    for(int i=0;i<n;i++)
    {
        cin>>x;
        result.push_back(x);
    }
    if(!insert(begin))
    {
        merge(begin);
    }
    return 0;
}
bool insert(vector <int> a)
{
    int i,j,k;
    bool flag=false;
    for( i=1;i<=n;i++)
    {
        /*  真*插入排序
        int m=a[i];
        for(j=0;j<i;j++)
        {
            if(a[i]>=a[j])
                continue;
            else
            {
                for(k=i;k>j;k--)
                {
                    a[k]=a[k-1];
                }
                a[j]=m;
            }
        }
            */
        sort(a.begin(),a.begin()+i,cmp);//伪*插入排序
        if(flag)
        {
            if(!check(a,result))//找一个结果改变的合集
            {
            cout<<"Insertion Sort"<<endl;
            for(int i=0;i<n-1;i++)
                cout<<a[i]<<" ";
            cout<<a[n-1]<<endl; 
                return true;
            }
        }
        if(!flag&&check(a,result))
        {
            flag=true;
        }
    }
    return false;
}
bool merge(vector <int> a)
{
    bool flag=false;
    int k=1;
    while(k<=n)
    {
        k=k*2;
        for(int i=0;i<n;)
        {
            if(i+k<=n-1)
                sort(a.begin()+i,a.begin()+i+k,cmp);
            else 
                sort(a.begin()+i,a.end(),cmp);
            i=i+k;
        }
            /*
        for(int i=0;i<n;)
        {
            if(i+k<=n-1)
                sort(&a[i],&a[i+k],cmp);
            else 
                sort(&a[i],&a[n-1],cmp);
            i=i+k;
        }
        不知道为什么，这样排序就会出错，为了这个调了半天。以后得注意*/ 
        if(flag)
        {
            if(!check(a,result))//找一个结果改变的合集
            {
                cout<<"Merge Sort"<<endl;
                for(int i=0;i<n-1;i++)
                    cout<<a[i]<<" ";
                cout<<a[n-1]<<endl;
                    return true;
            }
        }
        if(!flag&&check(a,result))
        {
            flag=true;
        }
    }
    return false;
}
bool cmp(int a,int b)
{
    return a<b;
}