查找最小的破坏连续性的数字

 

c#

public static class MyExtensions

{
 
    /// <summary>
 
    /// Finds the missing numbers in a list.
 
    /// </summary>
 
    /// <param name="list">List of numbers</param>
 
    /// <returns>Missing numbers</returns>
 
    public static IEnumerable<int> FindMissing(this List<int> list)
 
    {
 
        // Sorting the list
 
        list.Sort();



        // First number of the list
 
        var firstNumber = list.First();

// Last number of the list
 
        var lastNumber = list.Last();



        // Range that contains all numbers in the interval
　　　　 // [ firstNumber, lastNumber ]
        var range = Enumerable.Range(firstNumber, lastNumber - firstNumber);



        // Getting the set difference
 
        var missingNumbers = range.Except(list);



        return missingNumbers;
 
    }
}
}

 

 

 

java

从1开始 

public static int findFirstMissing(int ar[],
                      int size)
    {
        int a = 0, b = size - 1;
        int mid = 0;
        while ((b - a) > 1)
        {
            mid = (a + b) / 2;
            if ((ar[a] - a) != (ar[mid] - mid))
                b = mid;
            else if ((ar[b] - b) != (ar[mid] - mid))
                a = mid;
            else
                return ar[size-1]+1;
        }
        mid = a + (b -a)/2;
        return (ar[mid] + 1);
    }

 

 

 c++

int search(int ar[], int size)
{
int a = 0, b = size - 1;
int mid;
while ((b - a) > 1) {
mid = (a + b) / 2;
if ((ar[a] - a) != (ar[mid] - mid))
b = mid;
else if ((ar[b] - b) != (ar[mid] - mid))
a = mid;
}
return (ar[a] + 1);
}

 

 

#include <boost/range/counting_range.hpp>
#include <boost/range/irange.hpp>
#include <boost/iterator/counting_iterator.hpp>


auto i = mismatch(l.begin(), l.end(), boost::counting_range(1100, 1111).begin());

if (i.first == l.end()) {

}
else
std::cout << "the first missing number is " << *i.second << '\n';

 

 

 

 

 

 

 

 

 

 

 

 

参考:

https://www.leniel.net/2009/10/finding-missing-numbers-in-list-csharp.html

https://www.geeksforgeeks.org/find-the-missing-number-in-a-sorted-array/