P8647 [蓝桥杯 2017 省 AB] 分巧克力
AC

import java.util.Scanner;public class Main {static int n,k;static final int N = 100010;static int[] a = new int[N];static int[] b = new int[N];public static boolean check(int x) {int ans = 0;for(int i=1;i<=n;i++)ans+=(a[i]/x)*(b[i]/x);return ans>=k;}public static void main(String[] args) {Scanner sc = new Scanner(System.in);n = sc.nextInt();k = sc.nextInt();for(int i=1;i<=n;i++) {a[i] = sc.nextInt();b[i] = sc.nextInt();}int l = 1,r = 100010;while(l<r) {int mid = (l+r+1)/2;if(check(mid))	l = mid;else	r = mid-1;}System.out.println(l);}
}

P8772 [蓝桥杯 2022 省 A] 求和
AC

import java.util.Scanner;public class Main {static final int N = 200010;static int[] res = new int[N];static int[] b = new int[N];public static void main(String[] args){Scanner sc = new Scanner(System.in);int n = sc.nextInt();for(int i=1;i<=n;i++)res[i] = sc.nextInt();for(int i=1;i<=n;i++) {b[i] = b[i-1] + res[i];}long sum = 0;long t = b[n];for(int i=1;i<=n;i++) {sum+=res[i]*(t-b[i]);}System.out.println(sum);}
}