1089 Insert or Merge (25 分)

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 resuling 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

题意

给出数字n，再给出未排序序列以后经过某排序的某次中间结果序列，判断是插入排序还是归并排序。
插入排序的特点是，前面一部分有序，后面部分乱序（与原序一致）。
而归并排序则需模拟归并过程，若某次中间过程正好与题中所给相等，那么在归并一次即可输出。
注意：测试点4错误原因，判断是否为插入排序时需要考虑存在相等数的情况。

代码

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main() {
	int n;
	scanf("%d",&n);
	vector<int> a(n+1),b(n+1);
	for(int i=1; i<=n; i++) {
		scanf("%d",&a[i]);
	}
	for(int i=1; i<=n; i++) {
		scanf("%d",&b[i]);
	}
	//选择排序特点：前面有序，后面乱序（与原序一致）
	int k=2;
	while(b[k-1]<=b[k] && k<=n)	k++;
	int index=k;
	while(b[k]==a[k] && k<=n)	k++;
	if(k==n+1) {
		printf("Insertion Sort\n");
		sort(a.begin()+1,a.begin()+index+1);
	} else {
		printf("Merge Sort\n");
		int i,step,flag=0;	//flag判断该次归并后的结果是否与中间结果相等,相等为1，再归并一次后输出结果
		for(step=2; step/2<=n; step*=2) {
			for(i=1; i<=n; i+=step) {
				sort(a.begin()+i,a.begin()+min(i+step,n+1));
			}
			if(flag==0) {
				for(i=1; i<=n; i++) {
					if(a[i]!=b[i])	break;
				}
				if(i==n+1)	flag=1;
			} else	break;
		}
	}
	for(int i=1; i<=n; i++) {
		printf("%d",a[i]);
		if(i!=n)	printf(" ");
	}
	return 0;
}

标签：Sort,Insert,归并,PAT,sequence,int,1089,Merge,line
来源： https://blog.csdn.net/C_greenbird/article/details/120382158