//众神云集、群魔乱舞、以一抵百、砥砺前行//P1182 数列分段 Section II

题目描述

题目链接

题解

使用二分答案。二分的对象是数段的和，二分的范围是1-1e10。

代码如下：

#include<algorithm>
#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<cstring>
using namespace std;
#define ll long long
#define maxn 10000000000
ll read()
{
    ll ans=0,sign=1;
    char ch;
    ch=getchar();
    while(ch<'0'||ch>'9')
    {
        if(ch=='-')
            sign=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
    {
        ans=(ans<<1)+(ans<<3)+(ch^48);
        ch=getchar();
    }
    return ans;
}
int n,m;
ll a[100005];
bool cheak(ll tag)
{
    ll temp=0;
    ll sum=0;
for(int i=1;i<=n;i++)
{
    if(temp+a[i]<=tag)
        temp+=a[i];
    else
    {
        if(a[i]>tag)
            return 0;
        temp=a[i];
        sum++;
    }
}
return (sum+1)<=m;
}
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
        a[i]=read();
    ll x=1,y=maxn,ans;
    while(x<=y)
    {
        ll mid=x+(y-x)/2;
        if(cheak(mid))
        {
            y=mid-1;
            ans=mid;
        }
        else
            x=mid+1;
    }
    cout<<ans<<'\n';
    return 0;
}