solution

• 类型判断：插入排序中已排序的部分有序，未排序的和原数组元素相同；否则为归并排序
• 测试点6：对于归并排序的子序列长度，不能简单视为前k个有序则子序列长度就是k
  例如该测试用例的归并排序的子序列长度应该为2，而非4

8
2 1 3 8 5 2 4 6
1 2 3 8 2 5 4 6

#include<iostream>
#include<algorithm>
using namespace std;
const int maxn = 110;
int pre[maxn], did[maxn];
int main(){
	int n, cnt = 0, flag = 0, p, t;
	scanf("%d", &n);
	for(int i = 0; i < n; i++){
		scanf("%d", pre + i);
	}
	for(int i = 0; i < n; i++){
		scanf("%d", did + i);
	}
	for(p = 0; p < n; p++){
		if(p == 0) t = did[p];
		if(did[p] < t) break;
		t = did[p];
		cnt++;
	}
	for(; p < n; p++){
		if(did[p] != pre[p]){
			flag = 1;
			break;
		}
	}
	if(flag){
		printf("Merge Sort\n");
		t = 1;
		while(t){
			t = 0;
			for(int i = 0; i < n / cnt; i++){
				for(int j = i * cnt; j < (i + 1) * cnt - 1; j++){
					if(did[j] > did[j + 1]) t = 1;
				}
			}
			if(t) cnt /= 2;
		}
		cnt *= 2;
		for(int i = 0; i < n / cnt; i++){
			sort(did + i * cnt, did + (i + 1) * cnt);
		}
		sort(did + n / cnt * cnt, did + n);
	}
	else{
		printf("Insertion Sort\n");
		sort(did, did + cnt + 1);
	}
	for(int i = 0; i < n; i++){
		if(i) printf(" ");
		printf("%d", did[i]);
	}
	return 0;
}