feat(two-points): ✨双指针解决844

Author: descire

Two-Points/844/solution1.js

@@ -0,0 +1,55 @@
+/**
+ * https://leetcode-cn.com/problems/backspace-string-compare/
+ * 
+ * 844. 比较含退格的字符串
+ * 
+ * Easy
+ * 
+ * 94.66%
+ * 98.53%
+ */
+const backspaceCompare = (S, T) => {
+  let sIndex = S.length - 1
+  let tIndex = T.length - 1
+
+  while (sIndex >= 0 || tIndex >= 0) {
+    const s = S[sIndex] || ''
+    const t = T[tIndex] || ''
+
+    if (s === '#') {
+      sIndex = countIndex(S, sIndex)
+      continue
+    }
+    if (t === '#') {
+      tIndex = countIndex(T, tIndex)
+      continue
+    }
+
+    if (s !== t) {
+      return false
+    }
+    sIndex--
+    tIndex--
+  }
+
+  if (sIndex !== tIndex) {
+    return false
+  }
+  return true
+}
+
+function countIndex (str, index) {
+  let count = 1
+  for (let i = index - 1; i >= 0; i--) {
+    const s = str[i]
+    if (s === '#') {
+      count++
+      continue
+    }
+    count--
+    if (count === 0) {
+      return i - 1
+    }
+  }
+  return -1
+}