Method ceil

FindTheStudentThatWillReplaceTheChalk.java:22–38

(long prefixSum[], int remainingChalks)

class Solution {
    int n;
    public int ceil(long prefixSum[], int remainingChalks){
        int start = 0;
        int end = n-1;
        int ans=0;
        while(start<=end){
            int mid = start + (end-start)/2;
            if(prefixSum[mid] == remainingChalks){
                return mid+1;
            }else if(prefixSum[mid] < remainingChalks){
                start = mid+1;
            }else{
                ans = mid;
                end = mid-1;
            }
        }
        return ans;
    }
    public int chalkReplacer(int[] chalk, int k) {
        n = chalk.length;
        long prefixSum[] = new long[n];