1436: the number of columns segment II

1436: the number of columns segment II

 

answer

Dichotomous answer

    Our final answer is the value interval [max (a [i]), Σa [i]]

    Setting l = max (a [i]), r = Σa [i], mid continuously bipartite

    mid represents the maximum value and each segment, that is, each segment and not more than mid

    Lane into the check function, calculate the maximum value in the case of mid section may be divided into a number

    If the number of segments cnt> m, illustrate the mid small, it can be slightly larger

    If the number of segments cnt <= m, illustrate the mid big, then it will a little, because at this time cnt may be equal to m, this mid candidate answers recorded (if he is the real answer, the final output is that he, otherwise he will be updated to a smaller)

 

 

Code

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<string>
#include<queue>
#include<functional>

using namespace std;

int n,m,ans,l=0,r=0;
int a[100001];
int sum[100001]; 

int check(int x)
{
    int cnt=1,now=0;
    for(int i=1;i<=n;i++)
    {
        if(now+a[i]<=x) now+=a[i];
        else
        {
            cnt++;
            now=a[i];
        }
    }
    return cnt<=m;
}

int main()
{
     scanf("%d%d",&n,&m);
     for(int i=1;i<=n;i++)
     {
         scanf("%d",&a[i]);
         l=max(l,a[i]);
         r+=a[i];
     }
     
     while(l<=r)
     {
         int mid=(r+l)/2;
         if(check(mid)) 
         {
             ans=mid;
             r=mid-1;
        }
        else l=mid+1;
     }
       
    printf("%d",ans);
    
}