Number-of-students-unable-to-eat-lunch.java

class Solution {
    public int countStudents(int[] students, int[] sandwiches) {
        int sw0 = 0, sw1 = 0;
        for(int ch : students){
            if(ch == 0){
                sw0++;
            }
            else{
                sw1++;
            }
        }
        for(int sw : sandwiches){
            if(sw == 0 && sw0 == 0){
                return sw1;
            }
            if(sw == 1 && sw1 == 0){
                return sw0;
            }
            if(sw == 0){
                sw0--;
            }
            else{
                sw1--;
            }
        }
        return 0;
    }
}