LeetCode in Kotlin

962. Maximum Width Ramp

Medium

A ramp in an integer array nums is a pair (i, j) for which i < j and nums[i] <= nums[j]. The width of such a ramp is j - i.

Given an integer array nums, return the maximum width of a ramp in nums. If there is no ramp in nums, return 0.

Example 1:

Input: nums = [6,0,8,2,1,5]

Output: 4

Explanation: The maximum width ramp is achieved at (i, j) = (1, 5): nums[1] = 0 and nums[5] = 5.

Example 2:

Input: nums = [9,8,1,0,1,9,4,0,4,1]

Output: 7

Explanation: The maximum width ramp is achieved at (i, j) = (2, 9): nums[2] = 1 and nums[9] = 1.

Constraints:

• 2 <= nums.length <= 5 * 104
• 0 <= nums[i] <= 5 * 104

Solution

class Solution {
    fun maxWidthRamp(nums: IntArray): Int {
        val m = nums.size
        val dp = IntArray(m)
        var minInd = 0
        var ramp = 0
        for (i in 0 until m) {
            var prInd = minInd
            while (prInd > 0 && nums[i] >= nums[dp[prInd]]) {
                prInd = dp[prInd]
            }
            dp[i] = prInd
            if (nums[i] >= nums[prInd]) {
                ramp = ramp.coerceAtLeast(i - prInd)
            }
            minInd = if (nums[i] < nums[minInd]) i else minInd
        }
        return ramp
    }
}

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