Find first missing positive: Difference between revisions

=={{header|C++}}==

<syntaxhighlight lang="cpp">#include <iostream>

#include <unordered_set>

#include <vector>

int FindFirstMissing(const std::vector<int>& r)

{

// put them into an associative container

std::unordered_set us(r.begin(), r.end());

size_t result = 0;

while (us.contains(++result)); // find the first number that isn't there

return (int)result;

}

int main()

{

std::vector<std::vector<int>> nums {{1,2,0}, {3,4,-1,1}, {7,8,9,11,12}};

std::for_each(nums.begin(), nums.end(),

[](auto z){std::cout << FindFirstMissing(z) << " "; });

}</syntaxhighlight>

{{out}}

<pre>

3 2 1 </pre>