POJ 3273 Monthly Expense(二分)

#include <cstdio>
#include <iostream>
#include <cstring>
#define N 100050

using namespace std ;

int n , m ;     //n 代表天数，m代表要分成的区间数
int money
;

bool
Divide ( int const m_max )
{
int sum ;
sum = 0 ;
int group ;
group = 1 ;     //注意这个初始化
for ( int i = 1 ; i <= n ; i ++ )
{
int temp ;
temp = sum + money[i] ;
if ( temp <= m_max )  //注意这个判断
{
sum += money[i] ;
}
else
{
sum = money[i] ;
group ++ ;
}
}
return group > m ? true : false ;
//注意，当前分组大于实际分组则表示m_max 值小了,grou == m 的情况应返回false 题意:minimize the expenses of the fajomonth

}

void
Modify_Low_High ( int & low , int & high )
{
for ( int i = 1 ; i <= n ; i ++ )
{
high += money[i] ;
if ( low < money[i] )
{
low = money[i] ;
}
}
return ;
}

void
Solve ( )
{
int low , high ;       //定义二分搜索的上下限
low = high = 0 ;
Modify_Low_High ( low , high ) ;
int mid ;
while ( low <= high )       //二分搜索
{
mid = ( low + high ) / 2 ;
bool flag ;
flag = Divide ( mid ) ;
if ( flag ) //当前mid 作为highest spending 小了
{
low = mid + 1 ;
}
else
{
high = mid - 1 ;
}
}
printf ("%d\n" , mid ) ;
return ;
}

int
main ( )
{
while ( EOF != scanf ("%d%d" , & n , & m ) )
{
for ( int i = 1 ; i <= n ; i ++ )
{
scanf ("%d" , & money[i] ) ;
}
Solve ( ) ;
}
return 0 ;
}