29 顺时针打印矩阵
题目
输入一个矩阵，按照从外向里以顺时针打印出每一个数字，例如：输入如下矩阵，则依次打印出的数字为：1、2、3、4、8、12、16、15、14、13、9、5、6、7、11、10。
C++ 题解
class Solution {
public:
vector<int> printMatrix(vector<vector<int> > matrix) {
int row = matrix.size();
int col = matrix[0].size();
vector<int> res;
// 输入的二维数组非法，返回空的数组
if (row == 0 || col == 0)
return res;
// 定义四个关键变量，表示左上和右下的打印范围
int left = 0, top = 0, right = col - 1, bottom = row - 1;
while (left <= right && top <= bottom)
{
// left to right
for (int i = left; i <= right; ++i)
res.push_back(matrix[top][i]);
// top to bottom
for (int i = top + 1; i <= bottom; ++i)
res.push_back(matrix[i][right]);
// right to left
if (top != bottom)
for (int i = right - 1; i >= left; --i)
res.push_back(matrix[bottom][i]);
// bottom to top
if (left != right)
for (int i = bottom - 1; i > top; --i)
res.push_back(matrix[i][left]);
// 缩小打印范围
left++,top++,right--,bottom--;
}
return res;
}
};
python 题解
class Solution(object):
def printMatrix(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: List[int]
"""
if (not matrix or len(matrix)<=0 or len(matrix[0])<=0):
return []
rows=len(matrix)
columns=len(matrix[0])
left = 0; top = 0; right =columns-1; bottom=rows-1;
res = []
while (left <= right) and (top <= bottom):
# left to right
for i in range(left,right+1):
res.append(matrix[top][i])
# top to bottom
for i in range(top + 1,bottom+1):
res.append(matrix[i][right])
# right to left
if top != bottom:
for i in range(right - 1,left-1,-1):
res.append(matrix[bottom][i])
# bottom to top
if left != right:
for i in range(bottom - 1,top,-1):
res.append(matrix[i][left])
left+=1;top+=1;right-=1;bottom-=1;
return res
注意：
- python
range函数的左开右闭特性
