从最后一列
开始，以蛇形图案打印矩阵
原文:https://www . geeksforgeeks . org/print-matrix-in-snake-pattern-from-the-last-column/
给定一个由 n 行 n 列组成的二维矩阵。如下图所示，从第 n-1 列开始以蛇形方式打印该矩阵。
示例:
Input : mat[][] =
1 2 3
4 5 6
7 8 9
Output: 3 2 1 4 5 6 9 8 7
Input: mat[][] =
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
Output: 4 3 2 1 5 6 7 8 12 11 10 9 13 14 15 16
算法:
- 从属于第 0 行和第 n-1 列的右上角单元格开始遍历。
- 第一次移动总是向左(西)方向水平移动。
- 或者，在矩阵遍历期间进行水平和垂直移动。
- 在一次水平移动中，我们遍历多个单元格，直到到达矩阵的任何一个壁。
- 在水平移动中，如果行是奇数，我们向右(东)方向移动，否则我们向左(西)方向移动
- 在单次垂直移动中，我们沿向下方向遍历单个单元格。
以下是上述算法的实现:
C++
// C++ program for traversing a matrix from column n-1
#include <bits/stdc++.h>
using namespace std;
// Function used for traversing over the given matrix
void traverseMatrix(vector<vector<int> > mat, int n)
{
for (int i = 0; i < n; i++) {
if (i%2 == 1)
for (int j = 0; j < n; j++)
printf("%d ", mat[i][j]);
else
for (int j = n - 1; j >= 0; j--)
printf("%d ", mat[i][j]);
}
}
// Driver function
int main()
{
// number of rows and columns
int n = 5;
// 5x5 matrix
vector<vector<int> > mat{
{ 1, 2, 3, 4, 5 },
{ 6, 7, 8, 9, 10 },
{ 11, 12, 13, 14, 15 },
{ 16, 17, 18, 19, 20 },
{ 21, 22, 23, 24, 25 }
};
traverseMatrix(mat, n);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program for traversing a matrix from column n-1
class GFG {
// Function used for traversing over the given matrix
static void traverseMatrix(int[][] mat, int n)
{
for (int i = 0; i < n; i++) {
if (i % 2 == 1) {
for (int j = 0; j < n; j++) {
System.out.print(
Integer.toString(mat[i][j]) + " ");
}
}
else {
for (int j = n - 1; j >= 0; j--) {
System.out.print(
Integer.toString(mat[i][j]) + " ");
}
}
}
}
// Driver function
public static void main(String[] args)
{
// number of rows and columns
int n = 5;
// 5x5 matrix
int[][] mat = {
{ 1, 2, 3, 4, 5 },
{ 6, 7, 8, 9, 10 },
{ 11, 12, 13, 14, 15 },
{ 16, 17, 18, 19, 20 },
{ 21, 22, 23, 24, 25 }
};
traverseMatrix(mat, n);
System.exit(0);
}
}
Python 3
# Python3 program for traversing a matrix from column n-1
import sys;
# Function used for traversing over the given matrix
def traverseMatrix(mat, n):
for i in range(n):
if i & 1:
for j in range(n):
print(str(mat[i][j])+ "", end = " ")
else:
for j in range(n-1, -1, -1):
print(str(mat[i][j])+ "", end = " ")
# Driver function
if __name__ == '__main__':
# number of rows and columns
n = 5
# 5x5 matrix
mat =[
[1, 2, 3, 4, 5],
[6, 7, 8, 9, 10],
[11, 12, 13, 14, 15],
[16, 17, 18, 19, 20],
[21, 22, 23, 24, 25]
]
traverseMatrix(mat, n)
C
// CSHARP program for traversing a matrix from column n-1
using System;
using System.Linq;
class GFG {
// Function used for traversing over the given matrix
static void traverseMatrix(int[, ] mat, int n)
{
for (int i = 0; i < n; i++) {
if (i % 2 == 1) {
for (int j = 0; j < n; j++) {
Console.Write(mat[i, j].ToString() + " ");
}
}
else {
for (int j = n - 1; j >= 0; j--) {
Console.Write(mat[i, j].ToString() + " ");
}
}
}
}
// Driver function
public static void Main()
{
// number of rows and columns
int n = 5;
// 5x5 matrix
int[, ] mat = {
{ 1, 2, 3, 4, 5 },
{ 6, 7, 8, 9, 10 },
{ 11, 12, 13, 14, 15 },
{ 16, 17, 18, 19, 20 },
{ 21, 22, 23, 24, 25 }
};
traverseMatrix(mat, n);
}
}
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program for traversing a matrix from column n-1
# Function used for traversing over the given matrix
function traverseMatrix($mat, $n){
for($i = 0; $i < $n; $i++) {
if($i & 1) {
for($j = 0; $j < $n; $j++) {
print($mat[$i][$j]." ");
}
}
else {
for($j = $n - 1; $j >= 0; $j--) {
print($mat[$i][$j]." ");
}
}
}
}
// Driver function
# number of rows and columns
$n = 5;
# 5x5 matrix
$mat = array(
array(1, 2, 3, 4, 5),
array(6, 7, 8, 9, 10),
array(11, 12, 13, 14, 15),
array(16, 17, 18, 19, 20),
array(21, 22, 23, 24, 25)
);
traverseMatrix($mat, $n);
?>
Output:
5 4 3 2 1 6 7 8 9 10 15 14 13 12 11 16 17 18 19 20 25 24 23 22 21
时间复杂度 : O(N^2) 空间复杂度 : O(1)
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