feat: solve No.2289

Author: BaffinLee

2201-2300/2289. Steps to Make Array Non-decreasing.md

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+# 2289. Steps to Make Array Non-decreasing
+
+- Difficulty: Medium.
+- Related Topics: Array, Linked List, Stack, Monotonic Stack.
+- Similar Questions: Remove One Element to Make the Array Strictly Increasing.
+
+## Problem
+
+You are given a **0-indexed** integer array `nums`. In one step, **remove** all elements `nums[i]` where `nums[i - 1] > nums[i]` for all `0 < i < nums.length`.
+
+Return **the number of steps performed until **`nums`** becomes a **non-decreasing** array**.
+
+ 
+Example 1:
+
+```
+Input: nums = [5,3,4,4,7,3,6,11,8,5,11]
+Output: 3
+Explanation: The following are the steps performed:
+- Step 1: [5,3,4,4,7,3,6,11,8,5,11] becomes [5,4,4,7,6,11,11]
+- Step 2: [5,4,4,7,6,11,11] becomes [5,4,7,11,11]
+- Step 3: [5,4,7,11,11] becomes [5,7,11,11]
+[5,7,11,11] is a non-decreasing array. Therefore, we return 3.
+```
+
+Example 2:
+
+```
+Input: nums = [4,5,7,7,13]
+Output: 0
+Explanation: nums is already a non-decreasing array. Therefore, we return 0.
+```
+
+ 
+**Constraints:**
+
+
+	
+- `1 <= nums.length <= 105`
+	
+- `1 <= nums[i] <= 109`
+
+
+
+## Solution
+
+```javascript
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var totalSteps = function(nums) {
+    var dp = Array(nums.length).fill(0);
+    var stack = [];
+    for (var i = nums.length - 1; i >= 0; i--) {
+        while (stack.length && nums[i] > nums[stack[stack.length - 1]]) {
+            dp[i] = Math.max(dp[i] + 1, dp[stack.pop()]);
+        }
+        stack.push(i);
+    }
+    return Math.max(...dp);
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n).
+* Space complexity : O(n).