putZeroToEnd.cpp

/*
http://www.careercup.com/question?id=12986664
Push all the zero's of a given array to the end of the array. In place only. Ex 1,2,0,4,0,0,8 becomes 1,2,4,8,0,0,0
*/
#include <vector>
#include <iostream>
using namespace std;
void putZeroToEnd(vector<int> &vec) {
    // i for next non-zero num index
    // j for normal move forward index
    int i = 0;
    int j = 0;
    while (j < vec.size()) {
        if (vec[j] == 0) {
            j++;
        }
        else {
            vec[i] = vec[j];
            i++;
            j++;
        }
    }
    while (i < vec.size()) {
        vec[i] = 0;
        i++;
    }
}

int main() {
    vector<int> vec;
    vec.push_back(1);
    vec.push_back(2);
    vec.push_back(0);
    vec.push_back(4);
    vec.push_back(0);
    vec.push_back(0);
    vec.push_back(8);
    putZeroToEnd(vec);
    for (int i = 0; i < vec.size(); i++) {
        cout << vec[i] << " ";
    }
    cout << endl;
    system("pause");
}