Update 1638-count-substrings-that-differ-by-one-character.js

Author: everthis

1638-count-substrings-that-differ-by-one-character.js

@@ -25,3 +25,30 @@ const countSubstrings = function (s, t) {
   }
   return result
 }
+
+// another
+
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {number}
+ */
+const countSubstrings = function(s, t) {
+  let res = 0 ;
+  for (let i = 0; i < s.length; ++i) res += helper(s, t, i, 0);
+  for (let j = 1; j < t.length; ++j) res += helper(s, t, 0, j);
+  return res;
+};
+
+function helper(s,  t,  i,  j) {
+  let res = 0, pre = 0, cur = 0;
+  for (let n = s.length, m = t.length; i < n && j < m; ++i, ++j) {
+    cur++;
+    if (s.charAt(i) !== t.charAt(j)) {
+      pre = cur;
+      cur = 0;
+    }
+    res += pre;
+  }
+  return res;
+}