75. Sort Colors
Medium
Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white, and blue.
We will use the integers 0, 1, and 2 to represent the color red, white, and blue, respectively.
You must solve this problem without using the library’s sort function.
Example 1:
Input: nums = [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]
Example 2:
Input: nums = [2,0,1]
Output: [0,1,2]
Constraints:
n == nums.length
1 <= n <= 300
nums[i] is either 0, 1, or 2.
Follow-up: Could you come up with a one-pass algorithm using only constant extra space?
Constraints:
/**
* @param Integer[] $nums
* @return NULL
*/
function sortColors(&$nums) {
$l = 0;
$r = count($nums) – 1;
for ($i = 0; $i <= $r;) {
if ($nums[$i] == 0) {
list($nums[$i], $nums[$l]) = array($nums[$l], $nums[$i]);
$i++;
$l++;
} elseif ($nums[$i] == 1) {
$i++;
} else {
list($nums[$i], $nums[$r]) = array($nums[$r], $nums[$i]);
$r–;
}
}
}
}
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