Create 1087-brace-expansion.js

Author: everthis

1087-brace-expansion.js

@@ -0,0 +1,46 @@
+/**
+ * @param {string} S
+ * @return {string[]}
+ */
+const expand = function(S) {
+  const arr = []
+  let cur = ''
+  for (let i = 0, len = S.length; i < len; i++) {
+    const ch = S.charAt(i)
+    if (ch === '{') {
+      if (cur) arr.push(cur)
+      cur = []
+    } else if (ch === '}') {
+      arr.push(cur.sort())
+      cur = ''
+    } else if (ch === ',') {
+    } else {
+      if (typeof cur === 'string' || cur === '') {
+        cur += ch
+      } else {
+        cur.push(ch)
+      }
+    }
+  }
+  arr.push(cur)
+  const res = []
+  bt(arr, 0, '', res)
+  return res
+}
+function bt(arr, i, cur, res) {
+  if (i === arr.length) {
+    res.push(cur)
+    return
+  }
+  if (typeof arr[i] === 'string') {
+    cur += arr[i]
+    bt(arr, i + 1, cur, res)
+  } else {
+    for (let j = 0, len = arr[i].length; j < len; j++) {
+      let bak = cur
+      cur += arr[i][j]
+      bt(arr, i + 1, cur, res)
+      cur = bak
+    }
+  }
+}