80分求条

#include <bits/stdc++.h>
using namespace std;
long long l, n, k;
long long a[100005];

bool check(long long o) {
    if(o == 0) return false;
    long long cnt = 0, pr = 0;
    for(int i = 1; i <= n; i ++) {
        if(a[i] - pr > o) {
            cnt += (a[i] - pr) / o;
        }
        pr = a[i];
    }
    if(l - a[n] > o) cnt += (l - a[n]) / o;
    return cnt <= k;
}

int main() {
    cin >> l >> n >> k;
    for(int i = 1; i <= n; i ++) {
        cin >> a[i];
    }
    long long le = 0, ri = l + 1, ans = 0, mid;
    while(le <= ri) {
        mid = le + (ri - le) / 2;
        if(check(mid)) {
            ans = mid;
            ri = mid - 1;
        }
        else le = mid + 1;
    }
    cout << ans;
    return 0;
}