题目:Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
For example,Given the following matrix:
[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ]
思路:
四条线路法,定义up,right,down,left四个变量,先走最上面,再走最右边,再走最下面,再走最左边,条件结束标志为左等于右,上等于下。
代码:
class Solution { public: vector<int> spiralOrder(vector<vector<int>>& matrix) { vector<int>res; if(matrix.empty() || matrix[0].empty()){ return res; } int m=matrix.size(); int n=matrix[0].size(); int left=0,right=n-1; int up=0,down=m-1; while(up<=down&&left<=right){ for(int i=left;i<=right;i++){ res.push_back(matrix[up][i]); } for(int i=up+1;i<=down;i++){ res.push_back(matrix[i][right]); } if(up==down||left==right){ break; } for(int i=right-1;i>=left;i--){ res.push_back(matrix[down][i]); } for(int i=down-1;i>=up+1;i--){ res.push_back(matrix[i][left]); } up++; right--; down--; left++; } return res; } };