Update 1671-minimum-number-of-removals-to-make-mountain-array.js

Author: everthis

1671-minimum-number-of-removals-to-make-mountain-array.js

@@ -1,3 +1,41 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+const minimumMountainRemovals = function(nums) {
+  const inc = LIS(nums)
+  const dec = LIS(nums.slice().reverse()).reverse()
+  let res = 0
+  for(let i = 0, len = nums.length; i < len; i++) {
+    if(inc[i] > 1 && dec[i] > 1) res = Math.max(res, inc[i] + dec[i] - 1)
+  }
+  return nums.length - res
+};
+
+function LIS(arr) {
+  const stack = []
+  const res = []
+  for(let e of arr) {
+    if((stack.length && e > stack[stack.length - 1]) || stack.length === 0) {
+      stack.push(e)
+      res.push(stack.length)
+      continue
+    }
+    let l = 0, r = stack.length - 1
+    while(l < r) {
+      const mid = l + ((r - l) >> 1)
+      if(stack[mid] < e) l = mid + 1
+      else r = mid
+    }
+    stack[l] = e
+    res.push(stack.length)
+  }
+  
+  return res
+}
+
+// another
+
 /**
  * @param {number[]} nums
  * @return {number}