PTA ironic - enhanced version

Ironic enhanced version

Given a word of English, asking you to write a program, all the words of the sentence order reversed output.

Input formats:

Test input comprises a test case, given the string length does not exceed a total of 500,000 in a row. String composed of several words and a number of spaces, where the word is English letters (case is case) consisting of a string, a number between words separated by spaces.

Output formats:

Each test case output per line, output sentence after the reverse, and ensure that only one space between words.
Write topic and ideas: In the beginning I wanted to write a two-dimensional array, the results do half did not get out;
only fought other ideas think it should be replaced with a pointer to the array, and then was left out (a little embarrassed), and finally it no way, I can only be found a bit of code, learn about the big brother.
I decided to look at to understand the code, go back to thinking about their own ideas, try to use their own ideas to write again.
code show as below:

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

int main() {
	char str[500010];
	int len,real,head,count=0; 
	int i,j,k;
	gets(str);	//gets只有遇到回车才停止输入;
	len=strlen(str);	//len用来存储字符串长度； 
	for(i=len-1;i>=0;i--)	//从后往前进行
	{
		if(str[i]!=' ')
		{
			real=i;	//记录单词最后一个字母的位置 
			
			for(j=i-1;j>=0;j--)
			{
				if(str[j]==' ')	//向前遍历，遇到空格停下来 
				{
					break;                                                                                                                       
				}  
			} 
			
			head=j+1;	//指向空格的下一个空间，即单词的第一个字母
			if(count>0) //如果不是输出第一个单词，即原字符串最后一个单词，要输出一个相隔的空格
            {
                printf(" ");
            } 
            
			for(k=head; k<=real; k++)//从该单词的开头字符逐个输出到末尾字符
            {
                printf("%c", str[k]);
            }
            count++;                                                                     
            i=j;	//从遇到的空格那个位置开始，继续向前查询 
		}
	} 
	return 0;
}