## Introduction :

This post will show you how to check in an array of integers if it contains two numbers appeared *twice* or *more* than that using *Swift*. For example, if the array is *[1,2,3,4,1,3,5]*, the program will print *1* and *3* as outputs.

## Solution :

The easiest way to solve this problem is by using a *Dictionary*. We will use the below algorithm to solve it :

- Initialize one empty
*Int : Int*dictionary i.e. the keys are integer and values are also integer in this dictionary. - Iterate over the
*array*elements one by one. - For each number in the array, check if any key for that dictionary exists equal to the current number. If yes, increment its value by
*1.*Else, create one new*key-value*pairs with*key*equal to that number and*value*equal to zero. - Once the iteration will complete, we can check the dictionary to find out all the
*keys*with*value**2*or more than that.

## Swift program :

Let’s take a look at the program :

```
var m = [Int: Int]()
var arr: [Int] = [1,2,3,4,7,8,8,9,1,2]
for i in arr{
if let value = m[i] {
m[i] = value + 1
}else{
m[i] = 1
}
}
for i in m{
if(i.value > 1){
print(i.key)
}
}
```

It will print :

```
8
1
2
```