劍指Offer(十九):順時針打印矩陣
題目
輸入一個矩陣,按照從外向裏以順時針的順序依次打印出每一個數字,例如,如果輸入如下矩陣:
則依次打印出數組:1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10。
解題思路
將結果存入vector數組,從左到右,再從上到下,再從右到左,最後從下到上遍歷。
- C++
class Solution {
public:
vector<int> printMatrix(vector<vector<int> > matrix) {
int rows = matrix.size();
int cols = matrix[0].size();
vector<int> result;
int left = 0,right = cols - 1,top = 0,bottom = rows - 1;
while(left <= right && top <= bottom){
//從左到右
for(int i = left;i <= right;i++){
result.push_back(matrix[top][i]);
}
//從上到下
for(int j = top + 1; j <= bottom; j++){
result.push_back(matrix[j][right]);
}
//從右到左
if(top != bottom){
for(int i = right - 1; i >= left; --i){
result.push_back(matrix[bottom][i]);
}
}
//從下到上
if(left != right){
for(int i = bottom - 1; i > top; --i){
result.push_back(matrix[i][left]);
}
}
left++, top++, right--, bottom--;
}
return result;
}
};
- Python
# -*- coding:utf-8 -*-
class Solution:
# matrix類型爲二維列表,需要返回列表
def printMatrix(self, matrix):
# write code here
res = []
rows = len(matrix)
cols = len(matrix[0])
left,right,top,bottom = 0,cols - 1,0,rows - 1
while left<=right and top <= bottom:
for i in range(left,right+1):
res.append(matrix[top][i])
for j in range(top+1,bottom+1):
res.append(matrix[j][right])
if top != bottom:
for i in range(left,right)[::-1]:
res.append(matrix[bottom][i])
if left != right:
for i in range(top+1,bottom)[::-1]:
res.append(matrix[i][left])
left +=1
top += 1
right -=1
bottom -= 1
return res