剑指 Offer 21. 调整数组顺序使奇数位于偶数前面

https://leetcode-cn.com/problems/diao-zheng-shu-zu-shun-xu-shi-qi-shu-wei-yu-ou-shu-qian-mian-lcof/

双指针：
前后指针，就像快排的模板，判断奇偶，交换

正解代码

class Solution {
    public int[] exchange(int[] nums) {
    int len = nums.length;
    //if(len == 0) return -1;
    int l = 0, r = len - 1,tem;
    while(l < r){
        while(l < r && (nums[l] & 1) == 1) l++;
        while(l < r && (nums[r] & 1) == 0) r--;
        tem = nums[l];
        nums[l] = nums[r];
        nums[r] = tem;
    }
    return nums;
    }
}