I am only getting 33% my some test cases are wrong but why?

#1

import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int[] arr = new int[n];
int l = sc.nextInt();
for(int i = 0; i< n; i++) {
arr[i] = sc.nextInt();
}
System.out.println(binarySearch(arr, n, l));

}
public static int binarySearch(int[] arr, int n, int l) {
	int sum =0;
	int hi;
	int lo = 0;
	int ans = -1;
	for(int i = 0; i< n; i++) {
		sum += arr[i];
		lo = Math.max(arr[i], lo);
	}
	hi = sum;
	
	while(hi >= lo) {
		int mid = hi+ (lo-hi)/2;
		if(isvalid(arr, mid, l)) {
			hi = mid - 1;
			ans = mid;			
		}
		else 
			lo = mid + 1;
		
	}
	return ans;
}
public static boolean isvalid(int[] arr, int mid, int l) {
	int nl = 1;
	int sum = 0;
	for(int i = 0; i< arr.length; i++) {
		sum += arr[i];
		if(sum > mid) {
			nl++;
			sum = arr[i];
			if(nl > l)
				return false; 
		}
	}
	return true;
}

}

#2

Hey Ayush,
I went through your code and observed that:

  1. Your input format doesn’t matches with the expected input.
  2. In binarysearch: While calculating mid it should be lo+(hi-lo)/2;
  3. In isvalid: the input size can vary upto 10^8 thus we need to store the variables in Long to prevent Integer Overflow.
  4. In isvalid: You are directly adding the value in sum, what if we can’t add the element to the current sum. So for that we need to add a condition in isvalid:
   if(arr[i]+sum<=mid){
            sum += arr[i];
   }else { // (sum > mid)
  		nl++;
  		sum = arr[i]*1L;
            if(nl > l)
              return false; 
  	}

I have updated your code,
You can refer it for further aid (It is recommended to try solving the problem yourself first).

#3

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