LeetCode - 75. 颜色分类

看到这题目描述的第一感觉就是冒泡排序：

/**在这里插入图片描述
 * @param {number[]} nums
 * @return {void} Do not return anything, modify nums in-place instead.
 */
var sortColors = function(nums) {
    const len = nums.length - 1;
    for(let i = 0; i <= len; i++) {
        for (let j = i + 1; j <= len; j++) {
            if (nums[j] < nums[i]) {
                [nums[i], nums[j]] = [nums[j], nums[i]];
            }
        }
    }
};

结果速度和内存都快垫底了，换个思路：
用三个指针分成三部分，遍历一遍即可

/**
 * @param {number[]} nums
 * @return {void} Do not return anything, modify nums in-place instead.
 */
var sortColors = function(nums) {
    let right = nums.length - 1;
    let left = 0;
    let cur = 0;
    while(cur <= right) {
        switch(nums[cur]) {
            case 0:
                [nums[left], nums[cur]] = [nums[cur], nums[left]];
                left++;
                cur++;
                break;
            case 2: 
                [nums[right], nums[cur]] = [nums[cur], nums[right]];
                right--;
                break;
            default:
                cur++;
                break;
        }
    }
    
};