poj 3273 Monthly Expense

Description

Farmer John is an astounding accounting wizard and has realized he might run out of money to run the farm. He has already calculated and recorded the exact amount of money (1 ≤money_i ≤ 10,000) that he will need to spend each day over the nextN (1 ≤ N ≤ 100,000) days.

FJ wants to create a budget for a sequential set of exactly M (1 ≤ M ≤ N) fiscal periods called "fajomonths". Each of these fajomonths contains a set of 1 or more consecutive days. Every day is contained in exactly one fajomonth.

FJ's goal is to arrange the fajomonths so as to minimize the expenses of the fajomonth with the highest spending and thus determine his monthly spending limit.

Input

Line 1: Two space-separated integers: N andM
Lines 2..N+1: Line i+1 contains the number of dollars Farmer John spends on theith day

Output

Line 1: The smallest possible monthly limit Farmer John can afford to live with.

Sample Input

7 5100400300100500101400

Sample Output

500

Hint

If Farmer John schedules the months so that the first two days are a month, the third and fourth are a month, and the last three are their own months, he spends at most $500 in any month. Any other method of scheduling gives a larger minimum monthly limit.

 

 

题解：看起来没什么思路，看了disscus才知道原来是二分，设置二分的下限low=max（a[i]），high=sum（a[i]），通过比较mid能够设置的最大组数和m进行比较，从而确定二分的区间。

具体见：...戳戳戳...

代码：

#include <iostream>#include <cstdio>#include <cmath>using namespace std;int money[100010];int n,m;int disscus(int mid){    int group=1;    int sum=0;    for(int i=0;i<n;i++)        if(sum+money[i]<=mid)        sum+=money[i];    else        {        sum=money[i];        group++;    }    if(group>m)    return 0;    else return 1;}int main(){    while(scanf("%d%d",&n,&m)!=EOF)    {        int i,low=0,high=0;        for(i=0;i<n;i++)        {            scanf("%d",&money[i]);            low=max(low,money[i]);            high+=money[i];        }        int mid=(low+high)/2;        while(low<high)        {            if(!disscus(mid))            low=mid+1;            else high=mid-1;            mid=(low+high)/2;        }        printf("%d\n",mid);    }    return 0;}