PTA 09-排序2 Insert or Merge （25 分）

#include <bits/stdc++.h>

using namespace std;

int main()
{
	#ifdef ONLINE_JUDGE
	#else
	freopen("in.txt", "r", stdin);
	#endif
	
	int N;
	cin >> N;
	int v1[N], v2[N];
	int i, j;
	int len = 0; //len用來表示已排序長度 
	bool flag = true;//flag用來表示歸併排序的情況是否已經到達輸入的排序情況 或者用來表示是否爲插入排序 
	for(i = 0; i < N; i++){
		cin >> v1[i];
	}
	for(i = 0; i < N; i++){
		cin >> v2[i];
	}
	
	for(i = 0; i < N - 1; i++){
		if(v2[i] <= v2[i + 1]) len++;
		else break;
	} 
	for(i = len + 1; i < N; i++){
		if(v2[i] != v1[i]){
			flag = false;
			break;
		}
	} 
	
	if(flag){
		cout << "Insertion Sort" << endl;
		
		sort(v2, v2 + len + 2);
		
		for(i = 0; i < N; i++){
			if(i == 0) cout << v2[i];
			else cout << " " << v2[i];
		}
		
		return 0;
	}else{
		cout << "Merge Sort" << endl;
		
		flag = true;
		len = 1;
		
		while(flag){
			flag = false;
			
			for(i = 0; i < N; i++){
				if(v1[i] != v2[i]) flag = true; 
			}
			len *= 2;
			for(j = 0; j < N; j += len){
				sort(v1 + j, v1 + min(j + len, N));
			}
			
		}
		
		for(i = 0; i < N; i++){
			if(i == 0) cout << v1[i];
			else cout << " " << v1[i];
		}
		
		return 0;
	}
	
	return 0;
}