Spiral Matrix

题意是将一个二维数组，螺旋遍历出来，那么从Matrix[0][0]开始，提前记录好上下左右四个方向的边界，并且按照右下左上四个方向进行遍历。逻辑简单，代码复杂。代码如下:

public class spiralOrder {
    public static List<Integer> spiralOrder(int[][] matrix) {
        if(matrix.length==0)return new ArrayList<>();
        List<Integer> res = new ArrayList<>();
        int top=0,left=0,count=0,i=0,k=0;
        int right = matrix[0].length;
        int bottom = matrix.length;
        int sum = right * bottom;
        String direction = "right";
        while(res.size()<sum){
            if(direction.equals("right")){
                while(k<matrix[0].length && k<right){
                    res.add(matrix[i][k++]);
                    if(res.size()>=sum)break;
                }
                direction = "down";
                top++;
                k--;
                i++;
            }else if(direction.equals("down")){
                while(i<matrix.length && i<bottom){
                    res.add(matrix[i++][k]);
                    if(res.size()>=sum)break;
                }
                direction = "left";
                right--;
                i--;
                k--;
            }else if(direction.equals("left")){
                while(k>=0 && k>=left){
                    res.add(matrix[i][k--]);
                    if(res.size()>=sum)break;
                }
                direction = "up";
                bottom--;
                k++;
                i--;
            }else if(direction.equals("up")){
                while(i>=0 && i>=top){
                    res.add(matrix[i--][k]);
                    if(res.size()>=sum)break;
                }
                direction = "right";
                left++;
                i++;
                k++;
            }
        }
        return res;
    }

    public static void main(String[] args) {
        int[][] matrix = {{1,2,3,4,5},
                {6,7,8,9,10},
                {11,12,13,14,15},
                {16,17,18,19,20},
                {21,22,23,24,25}};
        List<Integer> res = spiralOrder(matrix);
        for(int i=0;i<res.size();i++){
            System.out.print(res.get(i)+",");
        }
    }
}