962.maximum width ramp(最大宽度坡)

Description

Given an array A of integers, a ramp is a tuple (i, j) for which i < j and A[i] <= A[j]. The width of such a ramp is j - i.

Find the maximum width of a ramp in A. If one doesn’t exist, return 0.


给定一个整数数组 A,坡是元组 (i, j),其中 i < j 且 A[i] <= A[j]。这样的坡的宽度为 j - i。

找出 A 中的坡的最大宽度,如果不存在,返回 0 。

题目链接:https://leetcode.com/problems/maximum-width-ramp/

Difficulty: medium

Example 1:

Input: [6,0,8,2,1,5]
Output: 4
Explanation: 
The maximum width ramp is achieved at (i, j) = (1, 5): A[1] = 0 and A[5] = 5.

Example 2:

Input: [9,8,1,0,1,9,4,0,4,1]
Output: 7
Explanation: 
The maximum width ramp is achieved at (i, j) = (2, 9): A[2] = 1 and A[9] = 1.

Note:

  • 2 <= A.length <= 50000
  • 0 <= A[i] <= 50000

分析

  • updating(Solution)

参考代码

class Solution(object):
def maxWidthRamp(self, A):
    ans = 0
    m = float('inf')
    for i in sorted(range(len(A)), key = A.__getitem__):
        ans = max(ans, i - m)
        m = min(m, i)
    return ans