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# Prime Sum Interviewbit Solution

Problem: Prime Sum

Problem Description:

Given an even number ( greater than 2 ), return two prime numbers whose sum will be equal to given number.

NOTE: A solution will always exist.

Example:

``` Input : 4
Output: 2 + 2 = 4  ```

If there are more than one solutions possible, return the lexicographically smaller solution.

```If [a, b] is one solution with a <= b,
and [c,d] is another solution with c <= d, then

[a, b] < [c, d]

If a < c OR a==c AND b < d. ```

Solution:

```vector<int> Solution::primesum(int A) {
bool vis[A+1];
memset(vis,false,sizeof(vis));
for(int i=2;i*i<=A;i++){
if(!vis[i]){
for(int j=2;i*j<A;j++){
vis[i*j]=true;
}
}
}
vector<int>res;

for(int i=2;i<=A/2;i++){
if(!vis[A-i]&&!vis[i]){
res.push_back(i);
res.push_back(A-i);
break;
}
}
return res;
}```

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