go: add «962. Maximum Width Ramp»

URL:	https://leetcode.com/problems/maximum-width-ramp/
Signed-off-by: Matej Focko <me@mfocko.xyz>

go/maximum-width-ramp.go

@@ -0,0 +1,21 @@
+package main
+
+func maxWidthRamp(nums []int) int {
+	st := make([]int, 0)
+
+	for i, x := range nums {
+		if len(st) == 0 || nums[st[len(st)-1]] > x {
+			st = append(st, i)
+		}
+	}
+
+	widest := 0
+	for j := len(nums) - 1; j >= 0; j-- {
+		for len(st) > 0 && nums[st[len(st)-1]] <= nums[j] {
+			widest = max(widest, j-st[len(st)-1])
+			st = st[:len(st)-1]
+		}
+	}
+
+	return widest
+}