add: 只出现一次的数字等

src/array/first-missing-prime-number.js

@@ -0,0 +1,69 @@
+// LintCode 681. 缺失的第一个素数 https://www.lintcode.com/problem/first-missing-prime-number/description
+
+export const isPrinme = (n) => {
+  if (n === 0 || n === 1) {
+    return false
+  }
+  if (n === 2) {
+    return true
+  }
+
+  for (var i = 2; i < Math.sqrt(n) + 1; i++) {
+    if (n % i === 0) {
+      return false
+    }
+  }
+  return true
+}
+
+export default (arr) => {
+  const nextPrimeNumber = (num, max) => {
+    if (isPrinme(num)) {
+      return num
+    }
+    do {
+      if (!max || num + 1 < max) {
+        num++
+      } else {
+        return false
+      }
+    } while (!isPrinme(num))
+    return num
+  }
+
+  arr = arr.filter(item => item > 0)
+
+  if (arr.length) {
+    const len = arr.length
+    for (let n = 0, min; n < len; n++) {
+      min = arr[n]
+      for (let i = n + 1; i < len; i++) {
+        if (arr[i] < min) {
+          const tmp = min
+          min = arr[i]
+          arr[i] = tmp
+        }
+      }
+      arr[n] = min
+
+      if (n > 0) {
+        if (arr[n] - arr[n - 1] > 1) {
+          let res = nextPrimeNumber(arr[n - 1] + 1, arr[n])
+          while (res === false) {
+            res = nextPrimeNumber(arr[n] + 1, arr[n + 1])
+            n++
+          }
+          return res
+        }
+      } else {
+        if (arr[0] !== 2) {
+          return 2
+        }
+      }
+    }
+
+    return nextPrimeNumber(arr.pop() + 1)
+  }
+
+  return 2
+}