Problem:
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You are given $n$ packages of $w_i$ kg from a belt conveyor in order ($i = 0, 1, ... n-1$). You should load all packages onto $k$ trucks which have the common maximum load $P$. Each truck can load consecutive packages (more than or equals to zero) from the belt conveyor unless the total weights of the packages in the sequence does not exceed the maximum load $P$.

Write a program which reads $n$, $k$ and $w_i$, and reports the minimum value of the maximum load $P$ to load all packages from the belt conveyor.

Input

In the first line, two integers $n$ and $k$ are given separated by a space character. In the following $n$ lines, $w_i$ are given respectively.

Output

Print the minimum value of $P$ in a line.

Constraints

$1 \leq n \leq 100,000$

$1 \leq k \leq 100,000$

$1 \leq w_i \leq 10,000$

Sample Input 1

5 3
8
1
7
3
9

Sample Output 1

10

If the first truck loads two packages of $\{8, 1\}$, the second truck loads two packages of $\{7, 3\}$ and the third truck loads a package of $\{9\}$, then the minimum value of the maximum load $P$ shall be 10.

Sample Input 2

4 2
1
2
2
6

Sample Output 2

6

If the first truck loads three packages of $\{1, 2, 2\}$ and the second truck loads a package of $\{6\}$, then the minimum value of the maximum load $P$ shall be 6.

Solution in JAVA (judge verdict: Accepted)



import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 *
 * @author baito
 */
public class Main {

    /**
     * @param args the command line arguments
     * @throws java.lang.Exception
     */
    static int n,k,total,max;
    static int[] w  ;
    public static void main(String[] args)throws Exception {
        // TODO code application logic here
        ContestScanner sc = new ContestScanner();
        n = sc.nextInt();
        k = sc.nextInt();
        w = new int[n];
        for (int i = 0; i < n; i++) {
            w[i] = sc.nextInt();
            total += w[i];
            max = Math.max(max, w[i]);
        }
        int answer = solve();
        System.out.println(answer);
    }
    public static int check(int max) {
        int sum = 0,i=0,j;
        for (j = 0; j < k;j++) {
            while(sum + w[i] <= max){
                sum += w[i];
                if(i == n - 1 )return n ;
                i++;
            }
            sum = 0;
            
        }
        return i;
    }
    public static int solve() {
        int first = max-1;
        int last = total  ,ans;
        while(- first + last > 1){
            int mid = (first + last)/2;
            ans = check(mid);
           // if(ans == n) return ans;
            if(ans >=  n ) last = mid ;
            else first = mid ;
        }
       //if(check(first) == n)return first;
        return last;
    }

    
    
}

//????????????????????????
class ContestScanner {
    
    private final BufferedReader reader;
    private String[] line;
    private int idx;
    
    public ContestScanner() throws FileNotFoundException {
        reader = new BufferedReader(new InputStreamReader(System.in));
    }
    
    public ContestScanner(String filename) throws FileNotFoundException {
        reader = new BufferedReader(new InputStreamReader(new FileInputStream(filename)));
    }
    //???????????? 

    public String readLine() throws Exception {
        return reader.readLine();
    }
    
    public String nextToken() throws IOException {
        if (line == null || line.length <= idx) {
            line = reader.readLine().trim().split(" ");
            idx = 0;
        }
        return line[idx++];
    }
    
    public long nextLong() throws IOException, NumberFormatException {
        return Long.parseLong(nextToken());
    }
    
    public int nextInt() throws NumberFormatException, IOException {
        return (int) nextLong();
    }
    
    public double nextDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(nextToken());
    }
}