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.
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
class Solution:
    def maxWidthRamp(self, A: List[int]) -> int:
        a = sorted(list(range(len(A))), key=lambda x: A[x])
        ans = 0
        m = float('inf')
        for i in a:
            ans = max(ans, i-m)
            m = min(m, i)
        return ans
            
            

class Solution:
    def maxWidthRamp(self, A: List[int]) -> int:
        a = sorted(list(range(len(A))), key=lambda x: A[x])
        ans = 0
        m = float('inf')
        for i in a:
            ans = max(ans, i-m)
            m = min(m, i)
        return ans
            
            
