只有测试点#3没过qwq 不知道是哪里有问题啊

#include<iostream>
using namespace std;
int a[50010];
int main() {
	int L, n, m, temp,pre=0;
	cin >> L >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> temp;
		a[i] = temp - pre;
		pre = temp;
	}
	a[n + 1] = L - temp;
	int l = 1, r = L,mid=(L+1)/2;
	while (l < r-1) {
		int total = 0;
		bool flag = 0;
		int tmp = m;
		for (int i = 1; i <= n+1; i++) {
			total += a[i];
			if (total < mid) {
				tmp--;
			}
			else {
				total = 0;
			}
			if (tmp < 0) {
				flag = 1; break;
			}
		}
		if (flag) {
			r = mid;
			mid = (l + r) / 2;
		}
		else {
			l = mid;
			mid = (l + r) / 2;
		}
	}
	cout << l;
}