Write a function nextinteger(v) which takes as input a vector v and as output returns the smallest positive integer which does not appear in v. For example, if the input is [1, 2, 3], the output would be 4. If the input is [4, 0, 1, -10], output =2
显示 更早的评论
This funtion worked for the vector [1,2,3,4] but not for [4, 1, 0, -10]
function [ ] = nextinteger(v)
n = max(v);
if n<0
n=0
else
n=n+1
end
end
2 个评论
Walter Roberson
2017-10-13
max([4, 1, 0, -10]) is 4, and you would transform that to 5. However, the question is not about one more than the largest value: it is about the first positive value that is not in the list. 1 is in the list, 2 is not, 3 is not, 4 is, 5 is not... smallest that is not in the list is 2.
Kristina Swais
2017-10-13
回答（2 个）
Andrei Bobrov
2017-10-13
编辑：Andrei Bobrov
2017-10-13
function out = nextinteger(v)
z = sort(v(v > 0));
s = setdiff(1:floor(z(end))+1,z);
out = s(1);
end
use
>> v = [6*rand(8,1) - 4;1;3];
>> v = v(randperm(10))
v =
-2.4935
0.88571
-2.4743
-1.9001
1.5756
1.0443
3
1
-2.5389
-2.8204
>> nextinteger(v)
ans =
2
>>
1 个评论
Seth Spatacean
2020-8-8
could you solve this using a while loop?
Currently your code only calculates the value 1+max(v), whereas you need to identify the first integer that is not in v, something like this:
function out = nextinteger(v)
tmp = 1:1+max(v); % positive integers
tmp = tmp(~ismember(tmp,v)); % not in v
out = tmp(1); % the first one
end
and tested:
>> nextinteger([1,2,3])
ans = 4
>> nextinteger([4,1,0,-10])
ans = 2
>>
2 个评论
Hussein Moussaoui
2018-4-15
is it possible to do this with only for, if and while loops?
Walter Roberson
2018-4-15
You will also need some indexing, some assignments, and some comparison operations.
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2017-10-13
2020-8-8
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