Largest Number After Digit Swaps by Parity

<-E 2231> Largest Number After Digit Swaps by Parity

class Solution {
public:
    int largestInteger(int num) {
        priority_queue<int> p;
        priority_queue<int> q;
        string nums = to_string(num);
        int n = nums.size();

        for(int i = 0; i < n; i++){
            int digit=nums[i] - '0';
            if(digit % 2)
                p.push(digit);
            else
                q.push(digit);
        }

        int answer = 0;
        for(int i = 0; i < n; i++) {
            answer = answer * 10;
            if((nums[i] - '0') % 2) {
                answer += p.top();
                p.pop();
            }
            else {
                answer += q.top();
                q.pop();
            }
        }
        return answer;
    }
};