CF1868F.LIS?
普及/提高-
通过率:0%
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题目描述
Entering senior high school life, Tom is attracted by LIS problems, not only the Longest Increasing Subsequence problem, but also the Largest Interval Sum problem. Now he gets a really interesting problem from his friend Daniel. However, it seems too hard for him to solve it, so he asks you for help.
Given an array a consisting of n integers.
In one operation, you do the following:
- Select an interval [l,r] ( 1≤l≤r≤n ), such that the sum of the interval is the largest among all intervals in the array a . More formally, i=l∑rai=1≤l′≤r′≤nmaxi=l′∑r′ai .
- Then subtract 1 from all elements al,al+1,…,ar .
Find the minimum number of operations you need to perform to make ai<0 for every 1≤i≤n .
输入格式
The first line of input contains a single integer n ( 1≤n≤5⋅105 ) — the length of the array a .
The second line contains n integers a1,a2,…,an ( −106≤ai≤106 ) — the elements of the array a .
输出格式
Print a single integer — the minimum number of operations.
输入输出样例
输入#1
5 1 2 3 4 5
输出#1
6
输入#2
6 -1 -5 -4 -1 -4 -7
输出#2
0
输入#3
11 0 1000000 1 -50000 2 998353 3 -100007 4 200943 0
输出#3
1936973
说明/提示
In the first example, you can do operations on intervals [1,5],[1,5],[2,5],[3,5],[4,5],[5,5] in such order. You may also do operations on intervals [1,5],[2,5],[3,5],[4,5],[5,5],[1,5] in such order.
In the second example, it's already satisfied that ai<0 for every 1≤i≤n . So you do not need to perform any operations.