原文:
给定一个数字 n，我们需要打印所有由手机键盘形成的 n 个数字模式。 注意:我们可以从手机小键盘的任意一个按键上、下、左、右移动，每个图案都包含唯一的按键。
示例:
input : n = 3
output : all 3 digit pattern are :
123, 125, 145, 147
236, 214, 258, 256, 254
321, 325, 369, 365
412, 456, 452, 458, 478
and so on ..
这个pg电子试玩链接的解决方案的想法是基于 dfs 的。我们一个接一个地选择所有键盘按键作为 n 位数的起始数字，之后，我们试图生成由该按键形成的所有 n 位数模式(使用 dfs，因为我们只能从该按键向上、向左、向右或向下移动)。
printpattern function (dfs function)
add current key to pattern
pattern = keypad[x][y]
.... make current key as visited
visited[x][y] = true;
... print pattern if size of pattern == n
call dfs for all 4 adjacent keypad key
__dfs_function
下面是上述想法的实现:
c
// c program to print all n digit patterns
// formed by mobile keypad.
#include
using namespace std;
// a function to check if a given cell (row, col)
// can be included in dfs
bool issafe(int x, int y, bool visited[][3])
{
// row number is in range, column number
// is in range and not yet visited
return (x >= 0 && x < 4 && y >= 0 &&
y < 3 && !visited[x][y]);
}
// a utility function to do dfs for a mobile keypad
// matrix. it only considers the 4 neighbors as
// adjacent vertice and print pattern of size n
void dfs(bool visited[][3], int keypad[][3], int n,
string pattern, int x, int y)
{
// add current number to string
pattern.push_back((keypad[x][y] '0'));
// print pattern
if (pattern.size() == n) {
cout << pattern << " ";
return;
}
// these arrays are used to get row and
// column
// numbers of 4 neighbours of a given cell
static int row[] = { 0, 1, 0, -1 };
static int col[] = { 1, 0, -1, 0 };
// mark this cell as visited
visited[x][y] = true;
// recur for all connected neighbours
for (int k = 0; k < 4; k )
if (issafe(x row[k], y col[k], visited)
&& keypad[x row[k]][y col[k]] != -1)
dfs(visited, keypad, n, pattern,
x row[k], y col[k]);
// unvisited
visited[x][y] = false;
pattern.pop_back();
}
void patternofsizek(int keypad[][3], int n)
{
// make a bool array to mark visited cells.
// initially all cells are unvisited
bool visited[4][3];
memset(visited, false, sizeof(visited));
// try to generate all pattern of size n
// by making every key of keypad as
// starting char of pattern
for (int i = 0; i < 4; i )
for (int j = 0; j < 3; j )
if (keypad[i][j] != -1)
dfs(visited, keypad, n, "", i, j);
}
// drive program to test above function.
int main()
{
int keypad[4][3] = { { 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 },
{ -1, 0, -1 } };
int n = 3;
patternofsizek(keypad, n);
return 0;
}
java 语言(一种计算机语言，尤用于创建网站)
// java program to print all n digit patterns
// formed by mobile keypad.
public class main
{
// a function to check if a given cell (row, col)
// can be included in dfs
static boolean issafe(int x, int y, boolean[][] visited)
{
// row number is in range, column number
// is in range and not yet visited
return (x >= 0 && x < 4 && y >= 0 &&
y < 3 && !visited[x][y]);
}
// a utility function to do dfs for a mobile keypad
// matrix. it only considers the 4 neighbors as
// adjacent vertice and print pattern of size n
static void dfs(boolean[][] visited, int[][] keypad, int n,
string pattern, int x, int y)
{
// add current number to string
pattern = pattern integer.tostring(keypad[x][y]);
// print pattern
if (pattern.length() == n) {
system.out.print(pattern " ");
return;
}
// these arrays are used to get row and
// column
// numbers of 4 neighbours of a given cell
int[] row = { 0, 1, 0, -1 };
int[] col = { 1, 0, -1, 0 };
// mark this cell as visited
visited[x][y] = true;
// recur for all connected neighbours
for (int k = 0; k < 4; k )
if (issafe(x row[k], y col[k], visited)
&& keypad[x row[k]][y col[k]] != -1)
dfs(visited, keypad, n, pattern,
x row[k], y col[k]);
// unvisited
visited[x][y] = false;
pattern = pattern.substring(0, pattern.length() - 1);
}
static void patternofsizek(int[][] keypad, int n)
{
// make a bool array to mark visited cells.
// initially all cells are unvisited
boolean[][] visited = new boolean[4][3];
for (int i = 0; i < 4; i )
{
for (int j = 0; j < 3; j )
{
visited[i][j] = false;
}
}
// try to generate all pattern of size n
// by making every key of keypad as
// starting char of pattern
for (int i = 0; i < 4; i )
{
for (int j = 0; j < 3; j )
{
if (keypad[i][j] != -1)
dfs(visited, keypad, n, "", i, j);
}
}
}
// driver code
public static void main(string[] args) {
int[][] keypad = { { 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 },
{ -1, 0, -1 } };
int n = 3;
patternofsizek(keypad, n);
}
}
// this code is contributed by divyesh072019.
python 3
# python3 program to print all n digit patterns
# formed by mobile keypad.
# a function to check if a given cell
# (row, col) can be included in dfs
def issafe(x, y, visited):
# row number is in range, column number
# is in range and not yet visited
return (x >= 0 and x < 4 and
y >= 0 and y < 3 and not visited[x][y])
# a utility function to do dfs for a mobile keypad
# matrix. it only considers the 4 neighbors as
# adjacent vertice and print pattern of size n
def dfs(visited, keypad, n, pattern, x, y):
# add current number to string
pattern = pattern str(keypad[x][y])
# print pattern
if (len(pattern) == n):
print(pattern, end = ' ')
return
# these arrays are used to get row and
# column
# numbers of 4 neighbours of a given cell
row = [ 0, 1, 0, -1 ]
col = [ 1, 0, -1, 0 ]
# mark this cell as visited
visited[x][y] = true
# recur for all connected neighbours
for k in range(0, 4):
if (issafe(x row[k],
y col[k], visited) and
keypad[x row[k]][y col[k]] != -1):
dfs(visited, keypad, n, pattern,
x row[k], y col[k])
# unvisited
visited[x][y] = false;
pattern = pattern[:-1]
def patternofsizek(keypad, n):
# make a bool array to mark visited cells.
# initially all cells are unvisited
visited = [[false for i in range(3)]
for j in range(4)]
# try to generate all pattern of size n
# by making every key of keypad as
# starting char of pattern
for i in range(4):
for j in range(3):
if (keypad[i][j] != -1):
dfs(visited, keypad, n,
"", i, j)
# drive code
if __name__=='__main__':
keypad = [ [ 1, 2, 3 ],
[ 4, 5, 6 ],
[ 7, 8, 9 ],
[ -1, 0, -1 ] ]
n = 3
patternofsizek(keypad, n)
# this code is contributed by rutvik_56
c
// c# program to print all n digit patterns
// formed by mobile keypad.
using system;
class gfg {
// a function to check if a given cell (row, col)
// can be included in dfs
static bool issafe(int x, int y, bool[,] visited)
{
// row number is in range, column number
// is in range and not yet visited
return (x >= 0 && x < 4 && y >= 0 &&
y < 3 && !visited[x,y]);
}
// a utility function to do dfs for a mobile keypad
// matrix. it only considers the 4 neighbors as
// adjacent vertice and print pattern of size n
static void dfs(bool[,] visited, int[,] keypad, int n,
string pattern, int x, int y)
{
// add current number to string
pattern = pattern (keypad[x,y]).tostring();
// print pattern
if (pattern.length == n) {
console.write(pattern " ");
return;
}
// these arrays are used to get row and
// column
// numbers of 4 neighbours of a given cell
int[] row = { 0, 1, 0, -1 };
int[] col = { 1, 0, -1, 0 };
// mark this cell as visited
visited[x,y] = true;
// recur for all connected neighbours
for (int k = 0; k < 4; k )
if (issafe(x row[k], y col[k], visited)
&& keypad[x row[k],y col[k]] != -1)
dfs(visited, keypad, n, pattern,
x row[k], y col[k]);
// unvisited
visited[x,y] = false;
pattern = pattern.substring(0, pattern.length - 1);
}
static void patternofsizek(int[,] keypad, int n)
{
// make a bool array to mark visited cells.
// initially all cells are unvisited
bool[,] visited = new bool[4,3];
for (int i = 0; i < 4; i )
{
for (int j = 0; j < 3; j )
{
visited[i,j] = false;
}
}
// try to generate all pattern of size n
// by making every key of keypad as
// starting char of pattern
for (int i = 0; i < 4; i )
{
for (int j = 0; j < 3; j )
{
if (keypad[i,j] != -1)
dfs(visited, keypad, n, "", i, j);
}
}
}
static void main() {
int[,] keypad = { { 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 },
{ -1, 0, -1 } };
int n = 3;
patternofsizek(keypad, n);
}
}
// this code is contributed by suresh07.
java 描述语言
输出:
123 125 145 147 236 256 258 254 214 369 365 325 321
456 458 452 478 412 569 563 589 580 587 547 541 523 521
698 658 654 652 632 789 780 785 745 741 896 874 856 854 852
980 987 985 965 963 089 087 085
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