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Commit 87dc8f8

Browse files
committed
20190701
1 parent 0554cec commit 87dc8f8

25 files changed

+48
-26
lines changed

‎code/lc1027.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@ public static int longestArithSeqLength(int[] A) {
1414
int[][] dp = new int[A.length][20000];
1515
for (int i = 0; i < A.length ; i++) {
1616
for (int j = 0; j < i ; j++) {
17-
int ind = A[i]-A[j]+10000;
17+
int ind = A[i]-A[j]+10000;//可能是负数,做一个偏移
1818
dp[i][ind] = dp[j][ind] + 1;
1919
res = Math.max(res, dp[i][ind]);
2020
}

‎code/lc114.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@
55
* 难度:Medium
66
* 分类:Tree, Depth-first Search
77
* 思路:就是节点间连接换一下,理清思路就行了,类似中序遍历
8-
* Tips:
8+
* Tips:lc426
99
*/
1010
public class lc114 {
1111
public class TreeNode {

‎code/lc125.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* 分类:Two Pointers, String
77
* 思路:两个指针。另一种是正则表达式替换数字,字母为空格,再反转,判断是否相等。
88
* Tips:记下另一种方法。第一种方法Bingo!
9-
* lc234, lc5
9+
* lc5, lc9, lc125, lc131, lc234, lc647
1010
*/
1111
public class lc125 {
1212
public static void main(String[] args) {

‎code/lc127.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,7 @@ public int ladderLength(String beginWord, String endWord, List<String> wordList)
2929
curr_str[j] = k;
3030
if(String.valueOf(curr_str).equals(endWord)) return level;
3131
if(wordList.contains(String.valueOf(curr_str))){
32-
wordList.remove(String.valueOf(curr_str));
32+
wordList.remove(String.valueOf(curr_str));//这要remove
3333
qu.add(String.valueOf(curr_str));
3434
}
3535
}

‎code/lc131.java

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,12 @@
88
* 难度:Medium
99
* 分类:Backtracking
1010
* 思路:典型回溯法,注意向res添加内容时要重新new一下
11-
* Tips:lc39
11+
* Tips: lc5, lc9, lc125, lc131, lc234, lc647
12+
* lc39
13+
* 判断是否为回文的方法:
14+
* 1. 从中心往两边扩充,中心可能是一个字符,也可能是两个字符
15+
* 2. dp,利用之前计算的结果,只判断边缘两个字符是否相等,从后往前dp
16+
* 3. 翻转了以后,判断两个串是否相等
1217
*/
1318
public class lc131 {
1419
public static void main(String[] args) {

‎code/lc218.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -39,7 +39,7 @@ public int compare(int[] o1, int[] o2) {
3939
int pre = 0;
4040
for (int i = 0; i < arr.length ; i++) {
4141
if(arr[i][1]>0){
42-
pr.add(-arr[i][1]);
42+
pr.add(-arr[i][1]);//默认是最小优先队列
4343
}else{
4444
pr.remove(arr[i][1]);
4545
}

‎code/lc22.java

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
66
* 分类:String, Backtracking
77
* 思路:回溯法的典型题目,按选优条件向前搜索,达到目标后就退回一步或返回
88
* 注意:递归法别忘了两块的拼接,例如n=4时,可以由2,2拼起来作为答案
9+
* lc32, lc22, lc301
910
*/
1011
import java.util.ArrayList;
1112
import java.util.HashSet;

‎code/lc227.java

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -21,7 +21,7 @@ public int calculate(String s) {
2121
if(Character.isDigit(chs[i])){
2222
num = num * 10 + chs[i]-'0';
2323
}
24-
if( !Character.isDigit(chs[i]) || i==chs.length-1 ){ //便利到最后,即使不是符号,也要计算
24+
if( !Character.isDigit(chs[i]) || i==chs.length-1 ){ //遍历到最后,即使不是符号,也要计算
2525
if(sign=='+'){
2626
st.push(num);
2727
}

‎code/lc234.java

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
66
* 分类:LinkedList, Two Pointers
77
* 思路:反转一半就行了,避免了空间开销
88
* Tips:很好的题,考了 Two Pointers, 还考了链表反转
9+
* lc5, lc9, lc125, lc131, lc234, lc647
910
*/
1011
public class lc234 {
1112
public class ListNode {

‎code/lc237.java

Lines changed: 3 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@
44
* 题意:删除链表中的一个节点,给的是这个节点,不知道前边的节点
55
* 难度:Easy
66
* 分类:Linked List
7-
* 思路:剑指Offer上有,拷贝下一个节点的内容到该节点,倒数第二个节点置空
7+
* 思路:剑指Offer上有,拷贝下一个节点的内容到该节点,删除下一个节点
88
* Tips:
99
*/
1010
public class lc237 {
@@ -17,12 +17,7 @@ public class ListNode {
1717
}
1818
}
1919
public void deleteNode(ListNode node) {
20-
ListNode pre = new ListNode(-1);
21-
while(node.next!=null) {
22-
node.val = node.next.val;
23-
pre = node;
24-
node = node.next;
25-
}
26-
pre.next = null;
20+
node.val = node.next.val;
21+
node.next = node.next.next;
2722
}
2823
}

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