Create 3297-count-substrings-that-can-be-rearranged-to-contain-a-string-i.js

Author: everthis

3297-count-substrings-that-can-be-rearranged-to-contain-a-string-i.js

@@ -0,0 +1,44 @@
+/**
+ * @param {string} word1
+ * @param {string} word2
+ * @return {number}
+ */
+var validSubstringCount = function (word1, word2) {
+  const mp1 = new Array(26).fill(0)
+  const mp2 = new Array(26).fill(0)
+  let missing = 0
+
+  for (const c of word2) {
+    mp1[c.charCodeAt(0) - 'a'.charCodeAt(0)]++
+  }
+
+  for (let i = 0; i < 26; i++) {
+    if (mp1[i] > 0) {
+      missing += mp1[i]
+    }
+  }
+
+  let res = 0
+  let left = 0
+  const n = word1.length
+
+  for (let right = 0; right < n; right++) {
+    const c = word1[right].charCodeAt(0) - 'a'.charCodeAt(0)
+    mp2[c]++
+    if (mp1[c] > 0 && mp2[c] <= mp1[c]) {
+      missing--
+    }
+
+    while (missing === 0) {
+      res += n - right
+      const left_char = word1[left].charCodeAt(0) - 'a'.charCodeAt(0)
+      if (mp1[left_char] > 0 && mp2[left_char] <= mp1[left_char]) {
+        missing++
+      }
+      mp2[left_char]--
+      left++
+    }
+  }
+
+  return res
+}