Luogu P1182 数列分段 Section II

Description：

对于给定的一个长度为N的正整数数列A-i,现要将其分成M(M≤N)段，并要求每段连续，且每段和的最大值最小。

Anakysis：

二分的边界还是不明白

Code

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int MAX_N = 100100;
int a[MAX_N],lb,ub,n,m;
bool C(int x)
{
    int cnt = 0,lastSum = 0;
    for(int i = 1;i <= n;++i)
    {
        if(lastSum + a[i] <= x) lastSum += a[i];
        else lastSum = a[i],cnt++;
    }
    if(cnt >= m) return 1;
    else return 0;
}
void solve()
{
    int mid;
    while(lb <= ub)
    {
        mid = (lb + ub) / 2;
        if(C(mid)) lb = mid + 1;
        else ub = mid - 1;
    }
    printf("%d
",lb);
}
int main()
{
    scanf("%d%d",&n,&m);
    for (int i = 1;i <= n;++i)
    {
        scanf("%d",&a[i]);
        ub += a[i];
        lb = max(lb,a[i]);
    }
    solve();
    return 0;
}