LeetCode-in-Java
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 * 1040 <= nums[i] <= 5 * 104
Solution
public class Solution {
public int maxWidthRamp(int[] nums) {
int m = nums.length;
int[] dp = new int[m];
int minInd = 0;
int ramp = 0;
for (int i = 0; i < m; i++) {
int prInd = minInd;
while (prInd > 0 && nums[i] >= nums[dp[prInd]]) {
prInd = dp[prInd];
}
dp[i] = prInd;
if (nums[i] >= nums[prInd]) {
ramp = Math.max(ramp, i - prInd);
}
minInd = nums[i] < nums[minInd] ? i : minInd;
}
return ramp;
}
}