selection sort			| insertion sort
--------------			| --------------
				|
7  5a 8  6  4  5b 3  9  1	| 7  5a 8  6  4  5b 3  9  1
^		        ^       | <---|
1  5a 8  6  4  5b 3  9  7       | 5a 7  8  6  4  5b 3  9  1
   ^		  ^             |       <
1  3  8  6  4  5b 5a 9  7       | 5a 7  8  6  4  5b 3  9  1
      ^	    ^                   |    <-----|
1  3  4  6  8  5b 5a 9  7       | 5a 6  7  8  4  5b 3  9  1
	 ^      ^               | <-----------|
1  3  4  5b 8  6  5a 9  7       | 4  5a 6  7  8  5b 3  9  1
	    ^	  ^             |	<---------|
1  3  4  5b 5a 6  8  9  7       | 4  5a 5b 6  7  8  3  9  1
	       ^                | <-----------------|
1  3  4  5b 5a 6  8  9  7       | 3  4  5a 5b 6  7  8  9  1
		  ^     ^       |		       <
1  3  4  5b 5a 6  7  9  8       | 3  4  5a 5b 6  7  8  9  1
		     ^  ^       | <-----------------------|
1  3  4  5b 5a 6  7  8  9       | 1  3  4  5a 5b 6  7  8  9

注意最後 5a 與 5b 的位置. Selection sort 不是 stable;
而 insertion sort 是 stable.