add: 环形数组循环

Author: yi-ge

README.md

@@ -1,8 +1,4 @@
-/**
- * @param {number[][]} matrix
- * @return {number[][]}
- */
-export const updateMatrix = function (matrix) {
+export const updateMatrix = function (matrix: number[][]): number[][] {
   if (matrix.length === 0) return []
 
   const m = matrix.length

src/array/01-matrix.js renamed to src/array/01-matrix.ts

@@ -1,8 +1,4 @@
-/**
- * @param {number[]} prices
- * @return {number}
- */
-var maxProfit = function (prices) {
+export const maxProfit = function (prices: number[]): number {
   let profit = 0
   for (let n = 1; n < prices.length; n++) {
     if (prices[n] > prices[n - 1]) profit += prices[n] - prices[n - 1]
@@ -11,4 +7,3 @@ var maxProfit = function (prices) {
   return profit
 }
 
-export default maxProfit

src/array/best-time-to-buy-and-sell-stock-ii.js renamed to src/array/best-time-to-buy-and-sell-stock-ii.ts

@@ -1,9 +1,4 @@
-/**
- * @param {number[]} nums
- * @param {number} target
- * @return {number}
- */
-export const search = function (nums, target) {
+export const search = function (nums: number[], target: number): number {
   if (!nums || nums.length === 0) return -1
 
   let start = 0

src/array/binary-search.js renamed to src/array/binary-search.ts

@@ -3,7 +3,7 @@
 // 空间复杂度 O(1)
 // 稳定
 
-export default (arr) => {
+export default (arr: number[]): number[] => {
   for (let n = 0, len = arr.length - 1, down = true; n < len; n++) {
     for (let i = 0, iLen = len - n; i < iLen; i++) {
       if (arr[i + 1] < arr[i]) {

src/array/bubble-sort.js renamed to src/array/bubble-sort.ts

@@ -1,4 +1,4 @@
-export default (flowerbed, n) => {
+export default (flowerbed: number[], n: number): boolean => {
   let max = 0
 
   // 前后各加一个0，避免判断边界情况。

src/array/can-place-flowers.js renamed to src/array/can-place-flowers.ts

@@ -0,0 +1,31 @@
+// LeetCode 457. 环形数组循环 https://leetcode-cn.com/problems/circular-array-loop/
+// LintCode 1229. 循环数组中的环 https://www.lintcode.com/problem/circular-array-loop/description
+
+const getNextIndex = (nums: number[], len: number, cur: number) => {
+  return ((cur + nums[cur]) % len + len) % len
+}
+
+export function circularArrayLoop (nums: number[]): boolean {
+  for (let i = 0, len = nums.length; i < len; i++) {
+    if (nums[i] === 0) continue
+    let slow = i, fast = getNextIndex(nums, len, i)
+    while (nums[slow] * nums[fast] > 0 && nums[slow] * nums[getNextIndex(nums, len, fast)] > 0) { // 方向相同
+      if (slow === fast) {
+        if (slow !== getNextIndex(nums, len, slow)) {
+          return true
+        } else {
+          break
+        }
+      }
+      slow = getNextIndex(nums, len, slow)
+      fast = getNextIndex(nums, len, getNextIndex(nums, len, fast))
+    }
+    let add = i
+    while (nums[add] * nums[getNextIndex(nums, len, add)] > 0) {
+      const tmp = add
+      add = getNextIndex(nums, len, add)
+      nums[tmp] = 0
+    }
+  }
+  return false
+}

src/array/circular-array-loop.js

@@ -0,0 +1,9 @@
+import { maxProfit } from '../../src/array/best-time-to-buy-and-sell-stock-ii'
+
+test('maxProfit', () => {
+  expect(maxProfit([7, 1, 5, 3, 6, 4])).toBe(7)
+  expect(maxProfit([1, 2, 3, 4, 5])).toBe(4)
+  expect(maxProfit([7, 6, 4, 3, 1])).toBe(0)
+  expect(maxProfit([])).toBe(0)
+  expect(maxProfit([2, 1, 2, 0, 1])).toBe(2)
+})

src/array/circular-array-loop.ts

@@ -0,0 +1,7 @@
+import canPlaceFlowers from '../../src/array/can-place-flowers'
+
+test('canPlaceFlowers', () => {
+  expect(canPlaceFlowers([1, 0, 0, 0, 1], 1)).toBeTruthy()
+  expect(canPlaceFlowers([1, 0, 0, 0, 1], 2)).toBeFalsy()
+  expect(canPlaceFlowers([1, 0, 0, 0, 1, 0, 0], 2)).toBeTruthy()
+})

test/array/01-matrix.test.js renamed to test/array/01-matrix.test.ts

@@ -1,4 +1,4 @@
-import circularArrayLoop from '../../src/array/circular-array-loop'
+import { circularArrayLoop } from '../../src/array/circular-array-loop'
 
 test('circularArrayLoop', () => {
   expect(circularArrayLoop([2, -1, 1, 2, 2])).toEqual(true)