题目:
输入一个矩阵,按照从外向里以顺时针的顺序依次打印出每一个数字,例如,如果输入如下矩阵: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
思路:
首先确定矩阵的行数和列数,初始化4个变量:left = 0;right = col-1;top = 0;bottom = row-1。然后按照从左向后、从上向下、从右向左、从下向上的顺序打印即可。需要注意的是,在打印从右向左时,需要判断top是否等于bottom;若相等,则不必打印该行;在打印从下向上时,需要判断left是否等于right,若相等,则不必打印该列。
代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 class Solution { 2 public: 3 vector<int> printMatrix(vector<vector<int> > matrix) { 4 int bottom = matrix.size() - 1; 5 int right = matrix[0].size() - 1; 6 int left = 0; 7 int top = 0; 8 vector<int> result; 9 while (left <= right && top <= bottom) { 10 //从左向右 11 for (int i = left; i <= right; i++) 12 result.push_back(matrix[top][i]); 13 //从上向下 14 for (int i = top + 1; i <= bottom; i++) 15 result.push_back(matrix[i][right]); 16 if (top != bottom) 17 //从右向左 18 for (int i = right - 1; i >= left; i--) 19 result.push_back(matrix[bottom][i]); 20 if (left != right) 21 //从下向上 22 for (int i = bottom - 1; i >= top + 1; i--) 23 result.push_back(matrix[i][left]); 24 left++; 25 right--; 26 top++; 27 bottom--; 28 } 29 return result; 30 } 31 };