原文：
给定 2d 数组，任务是以反螺旋形式打印矩阵：
示例：
输出：16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1。
input : arr[][4] = {1, 2, 3, 4
5, 6, 7, 8
9, 10, 11, 12
13, 14, 15, 16};
output : 10 11 7 6 5 9 13 14 15 16 12 8 4 3 2 1
input :arr[][6] = {1, 2, 3, 4, 5, 6
7, 8, 9, 10, 11, 12
13, 14, 15, 16, 17, 18};
output : 11 10 9 8 7 13 14 15 16 17 18 12 6 5 4 3 2 1
想法很简单，我们 遍历矩阵，并将所有遍历的元素放入栈中。 最后从栈中逐一列出并打印它们。
c
// c program to print matrix in anti-spiral form
#include
using namespace std;
#define r 4
#define c 5
void antispiraltraversal(int m, int n, int a[r][c])
{
int i, k = 0, l = 0;
/* k - starting row index
m - ending row index
l - starting column index
n - ending column index
i - iterator */
stack stk;
while (k <= m && l <= n)
{
/* print the first row from the remaining rows */
for (i = l; i <= n; i)
stk.push(a[k][i]);
k ;
/* print the last column from the remaining columns */
for (i = k; i <= m; i)
stk.push(a[i][n]);
n--;
/* print the last row from the remaining rows */
if ( k <= m)
{
for (i = n; i >= l; --i)
stk.push(a[m][i]);
m--;
}
/* print the first column from the remaining columns */
if (l <= n)
{
for (i = m; i >= k; --i)
stk.push(a[i][l]);
l ;
}
}
while (!stk.empty())
{
cout << stk.top() << " ";
stk.pop();
}
}
/* driver program to test above functions */
int main()
{
int mat[r][c] =
{
{1, 2, 3, 4, 5},
{6, 7, 8, 9, 10},
{11, 12, 13, 14, 15},
{16, 17, 18, 19, 20}
};
antispiraltraversal(r-1, c-1, mat);
return 0;
}
java
// java code for print matrix in antispiral form
import java.util.*;
class gfg {
public static void antispiraltraversal(int m, int n,
int a[][])
{
int i, k = 0, l = 0;
/* k - starting row index
m - ending row index
l - starting column index
n - ending column index
i - iterator */
stack stk=new stack();
while (k <= m && l <= n)
{
/* print the first row from the remaining
rows */
for (i = l; i <= n; i)
stk.push(a[k][i]);
k ;
/* print the last column from the remaining
columns */
for (i = k; i <= m; i)
stk.push(a[i][n]);
n--;
/* print the last row from the remaining
rows */
if ( k <= m)
{
for (i = n; i >= l; --i)
stk.push(a[m][i]);
m--;
}
/* print the first column from the remaining
columns */
if (l <= n)
{
for (i = m; i >= k; --i)
stk.push(a[i][l]);
l ;
}
}
while (!stk.empty())
{
system.out.print(stk.peek() " ");
stk.pop();
}
}
/* driver program to test above function */
public static void main(string[] args)
{
int mat[][] =
{
{1, 2, 3, 4, 5},
{6, 7, 8, 9, 10},
{11, 12, 13, 14, 15},
{16, 17, 18, 19, 20}
};
antispiraltraversal(mat.length - 1, mat[0].length - 1,
mat);
}
}
// this code is contributed by arnav kr. mandal.
python 3
# python 3 program to print
# matrix in anti-spiral form
r = 4
c = 5
def antispiraltraversal(m, n, a):
k = 0
l = 0
# k - starting row index
# m - ending row index
# l - starting column index
# n - ending column index
# i - iterator
stk = []
while (k <= m and l <= n):
# print the first row
# from the remaining rows
for i in range(l, n 1):
stk.append(a[k][i])
k = 1
# print the last column
# from the remaining columns
for i in range(k, m 1):
stk.append(a[i][n])
n -= 1
# print the last row
# from the remaining rows
if ( k <= m):
for i in range(n, l - 1, -1):
stk.append(a[m][i])
m -= 1
# print the first column
# from the remaining columns
if (l <= n):
for i in range(m, k - 1, -1):
stk.append(a[i][l])
l = 1
while len(stk) != 0:
print(str(stk[-1]), end = " ")
stk.pop()
# driver code
mat = [[1, 2, 3, 4, 5],
[6, 7, 8, 9, 10],
[11, 12, 13, 14, 15],
[16, 17, 18, 19, 20]];
antispiraltraversal(r - 1, c - 1, mat)
# this code is contributed
# by chitranayal
c
using system;
using system.collections.generic;
// c# code for print matrix in antispiral form
public class gfg
{
public static void antispiraltraversal(int m, int n, int[][] a)
{
int i, k = 0, l = 0;
/* k - starting row index
m - ending row index
l - starting column index
n - ending column index
i - iterator */
stack stk = new stack();
while (k <= m && l <= n)
{
/* print the first row from the remaining
rows */
for (i = l; i <= n; i)
{
stk.push(a[k][i]);
}
k ;
/* print the last column from the remaining
columns */
for (i = k; i <= m; i)
{
stk.push(a[i][n]);
}
n--;
/* print the last row from the remaining
rows */
if (k <= m)
{
for (i = n; i >= l; --i)
{
stk.push(a[m][i]);
}
m--;
}
/* print the first column from the remaining
columns */
if (l <= n)
{
for (i = m; i >= k; --i)
{
stk.push(a[i][l]);
}
l ;
}
}
while (stk.count > 0)
{
console.write(stk.peek() " ");
stk.pop();
}
}
/* driver program to test above function */
public static void main(string[] args)
{
int[][] mat = new int[][]
{
new int[] {1, 2, 3, 4, 5},
new int[] {6, 7, 8, 9, 10},
new int[] {11, 12, 13, 14, 15},
new int[] {16, 17, 18, 19, 20}
};
antispiraltraversal(mat.length - 1, mat[0].length - 1, mat);
}
}
// this code is contributed by shrikant13
输出：
12 13 14 9 8 7 6 11 16 17 18 19 20 15 10 5 4 3 2 1
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