原文:
给定两个正整数 n 和 k，打印所有长度为 k 的递增序列，使得每个序列中的元素都来自前 n 个自然数。
示例:
input: k = 2, n = 3
output: 1 2
1 3
2 3
input: k = 5, n = 5
output: 1 2 3 4 5
input: k = 3, n = 5
output: 1 2 3
1 2 4
1 2 5
1 3 4
1 3 5
1 4 5
2 3 4
2 3 5
2 4 5
3 4 5
强烈建议尽量减少浏览器，先自己试试这个。 这是一个很好的递归问题。其思想是创建一个长度为 k 的数组。该数组存储当前序列。对于数组中的每个位置，我们检查前一个元素，并一个接一个地放置大于前一个元素的所有元素。如果没有前一个元素(第一个位置)，我们把所有的数字从 1 到 n。
以下是上述想法的实现:
c
// c program to print all increasing sequences of
// length 'k' such that the elements in every sequence
// are from first 'n' natural numbers.
#include
using namespace std;
// a utility function to print contents of arr[0..k-1]
void printarr(int arr[], int k)
{
for (int i=0; i
java 语言(一种计算机语言，尤用于创建网站)
// java program to print all
// increasing sequences of
// length 'k' such that the
// elements in every sequence
// are from first 'n'
// natural numbers.
class gfg {
// a utility function to print
// contents of arr[0..k-1]
static void printarr(int[] arr, int k)
{
for (int i = 0; i < k; i )
system.out.print(arr[i] " ");
system.out.print("\n");
}
// a recursive function to print
// all increasing sequences
// of first n natural numbers.
// every sequence should be
// length k. the array arr[] is
// used to store current sequence
static void printsequtil(int n, int k,
int len, int[] arr)
{
// if length of current increasing
// sequence becomes k, print it
if (len == k)
{
printarr(arr, k);
return;
}
// decide the starting number
// to put at current position:
// if length is 0, then there
// are no previous elements
// in arr[]. so start putting
// new numbers with 1.
// if length is not 0,
// then start from value of
// previous element plus 1.
int i = (len == 0) ? 1 : arr[len - 1] 1;
// increase length
len ;
// put all numbers (which are
// greater than the previous
// element) at new position.
while (i <= n)
{
arr[len - 1] = i;
printsequtil(n, k, len, arr);
i ;
}
// this is important. the
// variable 'len' is shared among
// all function calls in recursion
// tree. its value must be
// brought back before next
// iteration of while loop
len--;
}
// this function prints all
// increasing sequences of
// first n natural numbers.
// the length of every sequence
// must be k. this function
// mainly uses printsequtil()
static void printseq(int n, int k)
{
// an array to store
// individual sequences
int[] arr = new int[k];
// initial length of
// current sequence
int len = 0;
printsequtil(n, k, len, arr);
}
// driver code
static public void main (string[] args)
{
int k = 3, n = 7;
printseq(n, k);
}
}
// this code is contributed by smitha.
python 3
# python3 program to print all
# increasing sequences of length
# 'k' such that the elements in
# every sequence are from first
# 'n' natural numbers.
# a utility function to
# print contents of arr[0..k-1]
def printarr(arr, k):
for i in range(k):
print(arr[i], end = " ");
print();
# a recursive function to print
# all increasing sequences of
# first n natural numbers. every
# sequence should be length k.
# the array arr[] is used to
# store current sequence.
def printsequtil(n, k,len1, arr):
# if length of current
# increasing sequence
# becomes k, print it
if (len1 == k):
printarr(arr, k);
return;
# decide the starting number
# to put at current position:
# if length is 0, then there
# are no previous elements
# in arr[]. so start putting
# new numbers with 1\. if length
# is not 0, then start from value
# of previous element plus 1.
i = 1 if(len1 == 0) else (arr[len1 - 1] 1);
# increase length
len1 = 1;
# put all numbers (which are greater
# than the previous element) at
# new position.
while (i <= n):
arr[len1 - 1] = i;
printsequtil(n, k, len1, arr);
i = 1;
# this is important. the variable
# 'len' is shared among all function
# calls in recursion tree. its value
# must be brought back before next
# iteration of while loop
len1 -= 1;
# this function prints all increasing
# sequences of first n natural numbers.
# the length of every sequence must be
# k. this function mainly uses printsequtil()
def printseq(n, k):
arr = [0] * k; # an array to store
# individual sequences
len1 = 0; # initial length of
# current sequence
printsequtil(n, k, len1, arr);
# driver code
k = 3;
n = 7;
printseq(n, k);
# this code is contributed by mits
c
// c# program to print all
// increasing sequences of
// length 'k' such that the
// elements in every sequence
// are from first 'n'
// natural numbers.
using system;
class gfg {
// a utility function to print
// contents of arr[0..k-1]
static void printarr(int[] arr, int k)
{
for (int i = 0; i < k; i )
console.write(arr[i] " ");
console.writeline();
}
// a recursive function to print
// all increasing sequences
// of first n natural numbers.
// every sequence should be
// length k. the array arr[] is
// used to store current sequence
static void printsequtil(int n, int k,
int len, int[] arr)
{
// if length of current increasing
// sequence becomes k, print it
if (len == k)
{
printarr(arr, k);
return;
}
// decide the starting number
// to put at current position:
// if length is 0, then there
// are no previous elements
// in arr[]. so start putting
// new numbers with 1.
// if length is not 0,
// then start from value of
// previous element plus 1.
int i = (len == 0) ? 1 : arr[len - 1] 1;
// increase length
len ;
// put all numbers (which are
// greater than the previous
// element) at new position.
while (i <= n)
{
arr[len - 1] = i;
printsequtil(n, k, len, arr);
i ;
}
// this is important. the
// variable 'len' is shared among
// all function calls in recursion
// tree. its value must be
// brought back before next
// iteration of while loop
len--;
}
// this function prints all
// increasing sequences of
// first n natural numbers.
// the length of every sequence
// must be k. this function
// mainly uses printsequtil()
static void printseq(int n, int k)
{
// an array to store
// individual sequences
int[] arr = new int[k];
// initial length of
// current sequence
int len = 0;
printsequtil(n, k, len, arr);
}
// driver code
static public void main ()
{
int k = 3, n = 7;
printseq(n, k);
}
}
// this code is contributed by ajit.
服务器端编程语言（professional hypertext preprocessor 的缩写）
java 描述语言
输出:
1 2 3
1 2 4
1 2 5
1 2 6
1 2 7
1 3 4
1 3 5
1 3 6
1 3 7
1 4 5
1 4 6
1 4 7
1 5 6
1 5 7
1 6 7
2 3 4
2 3 5
2 3 6
2 3 7
2 4 5
2 4 6
2 4 7
2 5 6
2 5 7
2 6 7
3 4 5
3 4 6
3 4 7
3 5 6
3 5 7
3 6 7
4 5 6
4 5 7
4 6 7
5 6 7
本文由阿琼供稿。如果你发现任何不正确的地方，请写评论，或者你想分享更多关于上面讨论的话题的信息
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