numrange
public class Solution {
public int count(ArrayList<Integer>A, int n, int k){
int start = 0, end = 0;
int count = 0;
int sum = A.get(0);
while(start < n && end < n){
if( sum < k ){
end++;
if(start <= end){
count += end - start;
}
if(end < n){
sum += A.get(end);
}
}
else{
sum -= A.get(start);
start++;
}
}
return count;
}
public int numRange(ArrayList<Integer> A, int B, int C) {
return count(A, A.size(), C + 1) - count(A, A.size(), B);
}
}