283. Move Zeroes

    /*
     * 283. Move Zeroes 
     * 12.7 by Mingyang 
     * 不用什么两个指针不指针的问题啦，一个一个慢慢来 需要把0换到后面去
     */
    public static void moveZeroes(int[] nums) {
        if (nums.length == 0 || nums == null)
            return;
        int start = -1;
        for (int i = 0; i < nums.length; i++) {
            // 找到第一个不是0的值，并且赋予start这个index
            if (nums[i] == 0 && start < 0) {
                start = i;
            }
            if (nums[i] != 0 && start >= 0) {
                swap(nums, i, start);
                i = start;
                start = -1;
            }
        }
    }    
    public static void swap(int A[], int i, int j) {
        int tmp = A[i];
        A[i] = A[j];
        A[j] = tmp;
    }
    // 哪里用什么换哦，没那么复杂啦，直接所有的前面全部填满，后面全部补0，不是换
    public void moveZeroes1(int[] nums) {
        int len=nums.length;
        int index=0;
        for(int i=0;i<len;i++){
            if(nums[i]!=0){
                nums[index]=nums[i];
                index++;
            }
        }
        for(int i=index;i<len;i++){
            nums[i]=0;
        }
    }
    // 我喜欢的思路，直接！两个指针
    public static void moveZeroes2(int[] nums) {
        if (nums.length <= 1)
            return;
        int first = 0;
        int sec = 0;
        while (sec < nums.length) {
            // find first zero element
            while (first < nums.length && nums[first] != 0) {
                first++;
            }
            if (first == nums.length)
                return;
            sec = first + 1;
            // find following first non-zero element
            while (sec < nums.length && nums[sec] == 0) {
                sec++;
            }
            if (sec == nums.length)
                return;
            swap(nums, first, sec);
        }
    }