title: Difference between Dutch National Flag problem and sorting
body: <p>I'm reading the <a href="https://en.wikipedia.org/wiki/Dutch_national_flag_problem" rel="nofollow">Dutch national flag problem</a> and I don't get it: why is this different from a simple sorting problem?</p>
  
  <p>I mean: if we assign 0 to the red color, 1 to white and 2 to blue and do a standard quicksort or whatever.. why should I not get the right answer?</p>
  
  <p>Am I missing something?</p>