Merge pull request #2621 from aadil42/patch-64

Create 1898-maximum-number-of-removable-characters.js

Author: aakhtar3

javascript/1898-maximum-number-of-removable-characters.js

@@ -0,0 +1,95 @@
+/**
+ * https://leetcode.com/problems/maximum-number-of-removable-characters/
+ * 
+ * Brute force
+ * Time O(removable.length * s.length) | Space O(n)
+ * @param {string} s
+ * @param {string} p
+ * @param {number[]} removable
+ * @return {number}
+ */
+var maximumRemovals1 = function(s, p, removable) {
+  let k = 0;
+  // removable.reverse();
+  s = s.split('');
+  p = p.split('');
+
+  for (let i = 0; i < removable.length; i++) {
+    s[removable[i]] = -1;
+    if (isSubSet1(s, p)) {
+      k++;
+      continue;
+    } 
+    return k;
+  }
+
+  return k;
+};
+
+// helper function.
+function isSubSet1(s, p) {
+  let i = 0;
+  let j = 0;
+
+  while (i < s.length && j < p.length) {
+    if (s[i] === p[j]) {
+      i++;
+      j++;
+    } else {
+      i++;
+    }
+  }
+
+  return j === p.length;
+}
+
+
+/**
+ * 
+ * Binary Search 
+ * n = length of string, k = length of removable
+ * Time O(log(k)*n) | Space O(1)
+ * @param {string} s
+ * @param {string} p
+ * @param {number[]} removable
+ * @return {number}
+ */
+var maximumRemovals = function(s, p, removable) {
+
+  let left = 0;
+  let right = removable.length - 1;
+  let k = 0;
+
+  while (left <= right) {
+    const mid = (left + right) >> 1;
+    const hash = new Set(removable.slice(0, mid + 1));
+
+    if (isSubSet(hash, s, p)) {
+      k = Math.max(k, mid + 1);
+      left = mid + 1;
+      continue;
+    }
+
+    right = mid - 1;
+  }
+
+  return k;
+};
+
+// helper function.
+function isSubSet(hash, s, p) {
+  let i = 0;
+  let j = 0;
+
+  while (i < s.length && j < p.length) {
+    if (s[i] === p[j] && !hash.has(i)) {
+      i++;
+      j++;
+      continue;
+    }
+
+    i++;
+  }
+
+  return j === p.length;
+}