add: 只出现一次的数字等

src/array/letter-combinations-of-a-phone-number.js

@@ -0,0 +1,46 @@
+// LeetCode 17. 电话号码的字母组合 https://leetcode-cn.com/problems/letter-combinations-of-a-phone-number/
+// LintCode 425. 电话号码的字母组合 https://www.lintcode.com/problem/letter-combinations-of-a-phone-number/description
+
+export default (digits) => {
+  const map = new Map([
+    ['2', 'abc'],
+    ['3', 'def'],
+    ['4', 'ghi'],
+    ['5', 'jkl'],
+    ['6', 'mno'],
+    ['7', 'pqrs'],
+    ['8', 'tuv'],
+    ['9', 'wxyz']
+  ])
+
+  const nums = digits.split('')
+
+  if (nums.length === 0) return []
+
+  const code = []
+
+  nums.forEach(item => {
+    if (map.get(item)) {
+      code.push(map.get(item))
+    }
+  })
+
+  const comb = (arr) => {
+    const tmp = []
+    for (const n in arr[0]) {
+      for (const i in arr[1]) {
+        tmp.push(`${arr[0][n]}${arr[1][i]}`)
+      }
+    }
+    arr.splice(0, 2, tmp)
+
+    if (arr.length > 1) {
+      comb(arr)
+    } else {
+      return tmp
+    }
+    return arr[0]
+  }
+
+  return code.length > 1 ? comb(code) : code[0].split('')
+}