1.insertion sort

#include <stdio.h>
#include <time.h>
#include <stdlib.h>

#define N 20

void main()
{
	int i,j,temp, a[N];

	srand((unsigned)time(0));
	puts("this is the 20 numbers,");
	for( i = 0; i < N; i++)
	{
		a[i] = rand()%100;	
		printf("%4d\t",a[i]);

	}
	puts("this is the end");

	for( i = 1; i < N; i++)
	{
	
	    temp = a[i];
		for( j = i-1; j >= 0; j--)
		{
			if(temp < a[j])	
			{
				a[j+1] = a[j];				
			}
			else
				
				break;
		}
		//这里为什么没有放在break上面，是因为当temp要放在第一位的时候，这一句不一定被执行
		a[j+1]=temp;
	
	}

	for(i = 0; i < N; i++)
		printf("%4d\t",a[i]);
}