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  1. Prepare
  2. Python
  3. Regex and Parsing
  4. Validating Credit Card Numbers
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Validating Credit Card Numbers

  • gvpkchandra
     + 2 comments

    Could you please share your solution,if had passed all the test cases? Here is my solution which is bit more efficient than the one suggested in the book; yet it has not passed all the test cases.

    #include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
using namespace std;

class MyQueue {
    public:
        stack<int> stack_newest_on_top, stack_oldest_on_top;
        void push(int x) {
            while(true != stack_oldest_on_top.empty()) {
                int tmp = stack_oldest_on_top.top();
                stack_oldest_on_top.pop();
                stack_newest_on_top.push(tmp);
            }
            stack_newest_on_top.push(x);
        }

        void pop() {
            if(true != stack_newest_on_top.empty()) {
                while(true != stack_newest_on_top.empty()) {
                    int tmp = stack_newest_on_top.top();
                    stack_newest_on_top.pop();
                    stack_oldest_on_top.push(tmp);
                }
                stack_oldest_on_top.pop();
            }
            else if (true != stack_oldest_on_top.empty()) {
                stack_oldest_on_top.pop();
            }
        }

        int front() {
            int rt_value = 0;
            if(true != stack_newest_on_top.empty()) {
                while(true != stack_newest_on_top.empty()) {
                    int tmp = stack_newest_on_top.top();
                    stack_newest_on_top.pop();
                    stack_oldest_on_top.push(tmp);
                }
                stack_oldest_on_top.pop();
            }
            else if (true != stack_oldest_on_top.empty()) {
                rt_value = stack_oldest_on_top.top();
            }
            return rt_value;
        }
};

int main() {
    MyQueue q1;
    int q, type, x;
    cin >> q;

    for(int i = 0; i < q; i++) {
        cin >> type;
        if(type == 1) {
            cin >> x;
            q1.push(x);
        }
        else if(type == 2) {
            q1.pop();
        }
        else cout << q1.front() << endl;
    }
    return 0;
}

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