求助全WA

#include <iostream>
using namespace std;
typedef long long ll;
ll n, m, l, r, mid, ans, a[100001];
bool P(ll x)
{
    ll tot = 0;
    for (ll i = 1; i <= n; i++)
    {
        ll num = a[i] - a[i - 1];
        if (num >= x)
        {
            if (num % x == 0) tot += max(0ll, ((num / x) - 1));
            else tot += max(0ll, (num / x));
            if (tot > m + 1) return false;
        }
    }
    return (tot <= (m + 1));
}
int main()
{
    cin >> n >> m;
    for (ll i = 1; i <= n; i++) cin >> a[i];
    l = 1, r = 1e8, mid = 0;
    while (l <= r)
    {
        mid = (l + r) >> 1;
        if (P(mid)) 
        {
            r = mid - 1;
            ans = mid;
        }
        else l = mid + 1;
    }
    cout << ans;
    return 0;
}