力扣 - 剑指 Offer 21. 调整数组顺序使奇数位于偶数前面

class Solution {
    public int[] exchange(int[] nums) {
        int length = nums.length;
        int left = 0;
        int right = length-1;

        while (left < right) {
            // 找偶书
            while (left < right && nums[left] % 2 == 1) {
                left++;
            }
            // 找奇数
            while (right > left && nums[right] % 2 == 0) {
                right--;
            }
            // 只有在left小于right情况下才交换
            if (left < right) {
                int temp = nums[left];
                nums[left] = nums[right];
                nums[right] = temp;
                // 交换完成后顺便指针移动一下
                left++;
                right--;
            }
        }

        return nums;
    }
}

class Solution {
    public int[] exchange(int[] nums) {
        int length = nums.length;
        int slow = 0;
        int fast = 0;

        while (slow < length && fast < length) {
            if (nums[fast] % 2 == 1) {
                if (fast != slow) {
                    int temp = nums[fast];
                    nums[fast] = nums[slow];
                    nums[slow] = temp;
                }
                slow++;
            }
            fast++;
        }
        return nums;
    }
}