Merge branch 'youngyangyang04:master' into leetcode-add-complexity-analysis-hashtable

problems/0070.爬楼梯完全背包版本.md

@@ -128,12 +128,12 @@ Java：
 class Solution {
     public int climbStairs(int n) {
         int[] dp = new int[n + 1];
-        int[] weight = {1,2};
+        int m = 2;
         dp[0] = 1;
 
-        for (int i = 0; i <= n; i++) {
+        for (int i = 1; i <= n; i++) { // 遍历背包
-            for (int j = 0; j < weight.length; j++) {
+            for (int j = 1; j <= m; j++) { //遍历物品
-                if (i >= weight[j]) dp[i] += dp[i - weight[j]];
+                if (i >= j) dp[i] += dp[i - j];
             }
         }
 
@@ -227,3 +227,4 @@ function climbStairs(n: number): number {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/0707.设计链表.md

@@ -133,6 +133,11 @@ public:
         LinkedNode* tmp = cur->next;
         cur->next = cur->next->next;
         delete tmp;
+        //delete命令指示释放了tmp指针原本所指的那部分内存，
+        //被delete后的指针tmp的值（地址）并非就是NULL，而是随机值。也就是被delete后，
+        //如果不再加上一句tmp=nullptr,tmp会成为乱指的野指针
+        //如果之后的程序不小心使用了tmp，会指向难以预想的内存空间
+        tmp=nullptr;
         _size--;
     }
 
@@ -1450,3 +1455,4 @@ impl MyLinkedList {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+