Merge branch 'youngyangyang04:master' into master

Author: Cwlrin

problems/0121.买卖股票的最佳时机.md

@@ -426,6 +426,46 @@ var maxProfit = function(prices) {
 };
 ```
 
+TypeScript：
+
+> 贪心法
+
+```typescript
+function maxProfit(prices: number[]): number {
+    if (prices.length === 0) return 0;
+    let buy: number = prices[0];
+    let profitMax: number = 0;
+    for (let i = 1, length = prices.length; i < length; i++) {
+        profitMax = Math.max(profitMax, prices[i] - buy);
+        buy = Math.min(prices[i], buy);
+    }
+    return profitMax;
+};
+```
+
+> 动态规划
+
+```typescript
+function maxProfit(prices: number[]): number {
+    /**
+        dp[i][0]: 第i天持有股票的最大现金
+        dp[i][1]: 第i天不持有股票的最大现金
+     */
+    const length = prices.length;
+    if (length === 0) return 0;
+    const dp: number[][] = [];
+    dp[0] = [-prices[0], 0];
+    for (let i = 1; i < length; i++) {
+        dp[i] = [];
+        dp[i][0] = Math.max(dp[i - 1][0], -prices[i]);
+        dp[i][1] = Math.max(dp[i - 1][0] + prices[i], dp[i - 1][1]);
+    }
+    return dp[length - 1][1];
+};
+```
+
+
+
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0122.买卖股票的最佳时机II（动态规划）.md

@@ -295,6 +295,42 @@ const maxProfit = (prices) => {
 }
 ```
 
+TypeScript：
+
+> 动态规划
+
+```typescript
+function maxProfit(prices: number[]): number {
+    /**
+        dp[i][0]: 第i天持有股票
+        dp[i][1]: 第i天不持有股票
+     */
+    const length: number = prices.length;
+    if (length === 0) return 0;
+    const dp: number[][] = new Array(length).fill(0).map(_ => []);
+    dp[0] = [-prices[0], 0];
+    for (let i = 1; i < length; i++) {
+        dp[i][0] = Math.max(dp[i - 1][0], dp[i - 1][1] - prices[i]);
+        dp[i][1] = Math.max(dp[i - 1][1], dp[i - 1][0] + prices[i]);
+    }
+    return dp[length - 1][1];
+};
+```
+
+> 贪心法
+
+```typescript
+function maxProfit(prices: number[]): number {
+    let resProfit: number = 0;
+    for (let i = 1, length = prices.length; i < length; i++) {
+        if (prices[i] > prices[i - 1]) {
+            resProfit += prices[i] - prices[i - 1];
+        }
+    }
+    return resProfit;
+};
+```
+
 
 
 -----------------------

problems/0123.买卖股票的最佳时机III.md

@@ -352,6 +352,36 @@ const maxProfit = prices => {
 };
 ```
 
+TypeScript：
+
+> 版本一
+
+```typescript
+function maxProfit(prices: number[]): number {
+    /**
+        dp[i][0]: 无操作; 
+        dp[i][1]: 第一次买入；
+        dp[i][2]: 第一次卖出；
+        dp[i][3]: 第二次买入；
+        dp[i][4]: 第二次卖出；
+     */
+    const length: number = prices.length;
+    if (length === 0) return 0;
+    const dp: number[][] = new Array(length).fill(0)
+        .map(_ => new Array(5).fill(0));
+    dp[0][1] = -prices[0];
+    dp[0][3] = -prices[0];
+    for (let i = 1; i < length; i++) {
+        dp[i][0] = dp[i - 1][0];
+        dp[i][1] = Math.max(dp[i - 1][1], -prices[i]);
+        dp[i][2] = Math.max(dp[i - 1][2], dp[i - 1][1] + prices[i]);
+        dp[i][3] = Math.max(dp[i - 1][3], dp[i - 1][2] - prices[i]);
+        dp[i][4] = Math.max(dp[i - 1][4], dp[i - 1][3] + prices[i]);
+    }
+    return Math.max(dp[length - 1][2], dp[length - 1][4]);
+};
+```
+
 Go:
 
 > 版本一：

problems/0142.环形链表II.md

@@ -370,7 +370,31 @@ ListNode *detectCycle(ListNode *head) {
 }
 ```
 
-
+Scala:
+```scala
+object Solution {
+  def detectCycle(head: ListNode): ListNode = {
+    var fast = head // 快指针
+    var slow = head // 慢指针
+    while (fast != null && fast.next != null) {
+      fast = fast.next.next // 快指针一次走两步
+      slow = slow.next // 慢指针一次走一步
+      // 如果相遇，fast快指针回到头
+      if (fast == slow) {
+        fast = head
+        // 两个指针一步一步的走，第一次相遇的节点必是入环节点
+        while (fast != slow) {
+          fast = fast.next
+          slow = slow.next
+        }
+        return fast
+      }
+    }
+    // 如果fast指向空值，必然无环返回null
+    null
+  }
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0242.有效的字母异位词.md

@@ -308,6 +308,32 @@ impl Solution {
 }
 ```
 
+
+Scala:
+```scala
+object Solution {
+  def isAnagram(s: String, t: String): Boolean = {
+    // 如果两个字符串的长度不等，直接返回false
+    if (s.length != t.length) return false
+    val record = new Array[Int](26) // 记录每个单词出现了多少次
+    // 遍历字符串，对于s字符串单词对应的记录+=1，t字符串对应的记录-=1
+    for (i <- 0 until s.length) {
+      record(s(i) - 97) += 1
+      record(t(i) - 97) -= 1
+    }
+    // 如果不等于则直接返回false
+    for (i <- 0 until 26) {
+      if (record(i) != 0) {
+        return false
+      }
+    }
+    // 如果前面不返回false，说明匹配成功，返回true，return可以省略
+    true
+  }
+}
+```
+
+
 C#：
 ```csharp
  public bool IsAnagram(string s, string t) {
@@ -326,6 +352,7 @@ C#：
         return true;
     }
 ```
+
 ## 相关题目
 
 * 383.赎金信

problems/背包理论基础01背包-1.md

@@ -380,53 +380,31 @@ func main() {
 ### javascript 
 
 ```js
-/**
- * 
- * @param {Number []} weight 
- * @param {Number []} value 
- * @param {Number} size 
- * @returns 
- */
-
-function testWeightBagProblem(weight, value, size) {
-const len = weight.length,
-dp = Array.from({length: len}).map(
-() => Array(size + 1))  //JavaScript 数组是引用类型	
-for(let i = 0; i < len; i++) {  //初始化最左一列，即背包容量为0时的情况
-dp[i][0] = 0;
-}
-for(let j = 1; j < size+1; j++) { //初始化第0行, 只有一件物品的情况
-if(weight[0] <= j) {
-dp[0][j] = value[0];
-} else {
-dp[0][j] = 0;
-}
-}
-	
-for(let i = 1; i < len; i++) {  //dp[i][j]由其左上方元素推导得出
-for(let j = 1; j < size+1; j++) {
-if(j < weight[i]) dp[i][j] = dp[i - 1][j];
-else dp[i][j] = Math.max(dp[i-1][j], dp[i-1][j - weight[i]] + value[i]);
-}
-}
+function testWeightBagProblem (weight, value, size) {
+    // 定义 dp 数组
+    const len = weight.length,
+          dp = Array(len).fill().map(() => Array(size + 1).fill(0));
 
-return dp[len-1][size] //满足条件的最大值
-}
+    // 初始化
+    for(let j = weight[0]; j <= size; j++) {
+        dp[0][j] = value[0];
+    }
 
-function testWeightBagProblem2 (wight, value, size) {
-  const len = wight.length, 
-    dp = Array(size + 1).fill(0);
-  for(let i = 1; i <= len; i++) {
-    for(let j = size; j >= wight[i - 1]; j--) {
-      dp[j] = Math.max(dp[j], value[i - 1] + dp[j - wight[i - 1]]);
+    // weight 数组的长度len 就是物品个数
+    for(let i = 1; i < len; i++) { // 遍历物品
+        for(let j = 0; j <= size; j++) { // 遍历背包容量
+            if(j < weight[i]) dp[i][j] = dp[i - 1][j];
+            else dp[i][j] = Math.max(dp[i - 1][j], dp[i - 1][j - weight[i]] + value[i]);
+        }
     }
-  }
-  return dp[size];
-}
 
+    console.table(dp)
+
+    return dp[len - 1][size];
+}
 
 function test () {
-  console.log(testWeightBagProblem([1, 3, 4, 5], [15, 20, 30, 55], 6));
+    console.log(testWeightBagProblem([1, 3, 4, 5], [15, 20, 30, 55], 6));
 }
 
 test();