54 螺旋矩阵

https://leetcode.cn/leetbook/read/top-interview-questions-hard/xw3ng2/

cost:

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        int x1 = 0, y1 = 0, x2 = matrix.size() - 1, y2 = matrix[0].size() - 1;
        enum State {
            Right,
            Up,
            Down,
            Left,
        };
        enum State state = Right;
        int x = x1, y = y1;
        int n = (x2 + 1) * (y2 + 1);
        vector<int> res;
        while (n > 0) {
            switch (state) {
            case Right:
                if (y == y2) {
                    state = Down;
                    res.push_back(matrix[x][y]);
                    x1++;
                    x = x1;
                } else {
                    res.push_back(matrix[x][y]);
                    y++;
                }
                break;
            case Down:
                if (x == x2) {
                    state = Left;
                    res.push_back(matrix[x][y]);
                    y2--;
                    y = y2;
                } else {
                    res.push_back(matrix[x][y]);
                    x++;
                }
                break;
            case Left:
                if (y == y1) {
                    state = Up;
                    res.push_back(matrix[x][y]);
                    x2--;
                    x = x2;
                } else {
                    res.push_back(matrix[x][y]);
                    y--;
                }
                break;
            case Up:
                if (x == x1) {
                    state = Right;
                    res.push_back(matrix[x][y]);
                    y1++;
                    y = y1;
                } else {
                    res.push_back(matrix[x][y]);
                    x--;
                }
                break;
            }
            n--;
        }
        return res;
    }
};