02旋转矩阵

旋转矩阵

给你一个 m 行 n 列的矩阵 matrix ，请按照 顺时针螺旋顺序 ，返回矩阵中的所有元素。

示例 1：

输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
输出：[1,2,3,6,9,8,7,4,5]

示例 2：

输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
输出：[1,2,3,4,8,12,11,10,9,5,6,7]

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 10
• -100 <= matrix[i][j] <= 100

public List<Integer> spiralOrder(int[][] matrix) {
  int m = matrix.length;
  int n = matrix[0].length;
  int left = 0;
  int right = n-1;
  int top = 0;
  int down = m-1;
  int size = m*n;

  List<Integer> res = new ArrayList<>(size);

  while (true){
    for (int i = left; i <= right ; i++) {
      res.add(matrix[top][i]);
    }
    top++;
    if(res.size()==size) return res;

    for (int i = top; i <= down  ; i++) {
      res.add(matrix[i][right]);
    }
    right--;
    if(res.size()==size) return res;

    for (int i = right; i >=left; i--) {
      res.add(matrix[down][i]);
    }
    down--;
    if(res.size()==size) return res;

    for (int i = down; i >= top ; i--) {
      res.add(matrix[i][left]);
    }
    left++;
    if(res.size()==size) return res;

  }


}