POJ 3273 Monthly Expense 二分枚举

题目：http://poj.org/problem?id=3273

二分枚举，据说是经典题，看了题解才做的，暂时还没有完全理解。。

 1 #include <stdio.h>

 2 #include <string.h>

 3 

 4 int n, m;

 5 int a[100000];

 6 

 7 bool judge(int x)

 8 {

 9     int money = 0, cnt = 1;

10     for(int i = 0; i < n; i++)

11     {

12         if(money + a[i] <= x)

13             money += a[i];

14         else

15         {

16             money = a[i];

17             cnt++;

18         }

19     }

20     if(cnt > m)

21         return 0;

22     else return 1;

23 }

24 

25 int main()

26 {

27     int low = 0, high = 0;

28     scanf("%d %d", &n, &m);

29     for(int i = 0; i < n; i++)

30     {

31         scanf("%d", &a[i]);

32         if(low < a[i])

33             low = a[i];

34         high += a[i];

35     }

36     int mid = (low + high) / 2;

37     while(low < high)

38     {

39         if(judge(mid))

40             high = mid - 1;

41         else low = mid + 1;

42         mid = (low + high) / 2;

43     }

44     printf("%d\n", mid);

45     return 0;

46 }

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