Spiral Matrix (Medium)

Description

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

Analysis

直接模拟。。

My Solution

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//C++
class Solution {
    vector<int> ans;
public:
    vector<int> spiralOrder(vector<vector<int> > &matrix) {
        int dx[] = {0,1,0,-1};
        int dy[] = {1,0,-1,0};
        int m    = matrix.size();
        if(m == 0)  return ans;
        int n    = matrix[0].size();
        if(n == 0)  return ans;
        int u = 0 ,d = m - 1 , l = 0, r = n - 1;
        int x = 0 , y = 0 , num = m*n , dir = 0;
        while(num){
            if(x>=u&&y>=l&&x<=d&&y<=r){
                ans.push_back(matrix[x][y]);
                num--;
                x+=dx[dir];
                y+=dy[dir];
            }
            else{
                x-=dx[dir];
                y-=dy[dir];
                if(dir == 0)    u++;
                else if(dir == 1)    r--;
                else if(dir == 2)    d--;
                else l++;
                dir = (dir+1)%4;
                x+=dx[dir];
                y+=dy[dir];
            }
        }
        return ans;
    }
};