# 1116.Print Zero Even Odd

Suppose you are given the following code:

`class ZeroEvenOdd {  public ZeroEvenOdd(int n) { ... }      // constructor  public void zero(printNumber) { ... }  // only output 0's  public void even(printNumber) { ... }  // only output even numbers  public void odd(printNumber) { ... }   // only output odd numbers}`

The same instance of ZeroEvenOdd will be passed to three different threads:

• Thread A will call zero() which should only output 0's.

• Thread B will call even() which should only ouput even numbers.

• Thread C will call odd() which should only output odd numbers.

Each of the thread is given a printNumber method to output an integer. Modify the given program to output the series 010203040506... where the length of the series must be 2n.

`Example 1:​Input: n = 2Output: "0102"Explanation: There are three threads being fired asynchronously. One of them calls zero(), the other calls even(), and the last one calls odd(). "0102" is the correct output.Example 2:​Input: n = 5Output: "0102030405"`

`class ZeroEvenOdd {private:    int n;    pthread_mutex_t t1= PTHREAD_MUTEX_INITIALIZER;    pthread_mutex_t t2 = PTHREAD_MUTEX_INITIALIZER;    pthread_mutex_t t3 = PTHREAD_MUTEX_INITIALIZER;    bool flag=true;public:    ZeroEvenOdd(int n) {        this->n = n;        pthread_mutex_lock(&t2) ;        pthread_mutex_lock(&t3) ;    }​    // printNumber(x) outputs "x", where x is an integer.    void zero(function<void(int)> printNumber) {        for(int i=0;i<n;i++)        {            pthread_mutex_lock(&t1);            printNumber(0);            flag ?        pthread_mutex_unlock(&t2) :  pthread_mutex_unlock(&t3);​        }​    }​    void even(function<void(int)> printNumber) {​        for(int i=1;i<=n;i+=2){          pthread_mutex_lock(&t2);          printNumber(i);          flag=false;          pthread_mutex_unlock(&t1);        }    }​    void odd(function<void(int)> printNumber) {        for(int i=2;i<=n;i+=2){        pthread_mutex_lock(&t3);        flag=true;        printNumber(i);        pthread_mutex_unlock(&t1);        }    }};`