1.check(int i)函数 检查当前长度i 在 N 块巧克力能分多少块相同大小的正方体 值为sum
如果sum>=要求分的块数返回true 否则返回false
2.图示

import java.util.Scanner;
public class Main {
    static int number;
    static int end = Integer.MIN_VALUE;
    static int [][]arr;
    static int N;
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        N = in.nextInt();
        number = in.nextInt();
        arr = new int[N][2];
        for(int i=0;i<N;i++){
            arr[i][0] = in.nextInt();
            arr[i][1] = in.nextInt();
        }
        for(int i=0;i<arr.length;i++){
            for(int j=0;j<arr[0].length;j++){
                if(end<arr[i][j]) end  = arr[i][j];
            }
        }
        binarySearch();
    }

    static void binarySearch() {
        int l = 1, r = end;
        while(l < r){
            int mid  = l+r+1 >>1;
            if(check(mid)) l = mid;
            else r = mid-1;
        }
        System.out.println(l);
    }

    static boolean check(int mid) {
        int sum = 0;
        for(int i=0;i<arr.length;i++){
                int n = (int) Math.floor(arr[i][0]/mid);
                int m = (int) Math.floor(arr[i][1]/mid);
                sum  = sum + n*m;
        }
        if(sum>=number) return true;
        else return false;
    }
}