二分搜索 POJ 3273 Monthly Expense

题目传送门

 /*
     题意：分成m个集合，使最大的集合值(求和)最小
     二分搜索：二分集合大小，判断能否有m个集合。
 */
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <cmath>
 using namespace std;

 const int MAXN = 1e5 + ;
 const int INF = 0x3f3f3f3f;
 int a[MAXN];
 int n, m;

 bool check(int tot) {
     int j = , sum = ;
     for (int i=; i<=m; ++i)    {
         sum = ;
         while (j <= n && sum + a[j] <= tot)    {
             sum += a[j++];
         }
         if (j == n + ) return true;
     }
     return false;
 }

 int main(void)  {       //POJ 3273 Monthly Expense
     //freopen ("POJ_3273.in", "r", stdin);

     while (scanf ("%d%d", &n, &m) == ) {
         int l = , r = ;
         for (int i=; i<=n; ++i)    {
             scanf ("%d", &a[i]);
             if (l < a[i])   l = a[i];
             r += a[i];
         }

         while (l < r)   {
             int mid = (l + r) >> ;
             if (check (mid))    r = mid;
             else    l = mid + ;
         }
         printf ("%d\n", l);
     }

     return ;
 }