P2678 [NOIP2015 提高组] 跳石头 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

 

d, n, m = map(int,input().split())

data = [0]
for i in range(n):
    value = int(input())
    data.append(value)
data.append(d)

def check(mid):
    now = 0
    cnt = 0
    for i in range(1,n+2):
        if abs(data[now]-data[i])<mid:
            cnt += 1
        else:
            now = i
    if cnt>m:
        return False
    else:
        return True

l = 0
r = d
while l<r:
    mid = (l + r + 1) // 2
    if check(mid) :
        l = mid
    else:
        r = mid-1

print(l)