刷题记录帖

public Object getOrDefault(Object key, Object defaultValue)
Parameters: This method accepts two parameter:

key: whose mapping is to be checked in this Properties object.
defaultValue: which is the default mapping of the key
Returns: This method returns the value fetched corresponding to this key, if present. If there is no such mapping, then it returns the defaultValue.

266. Palindrome Permutation
How to optimize the code.
怎样做code 优化
check if you can change two pass to a single pass.
on the fly.
Approach #4 Single Pass

dealling with odd or even number of occurence: use set.
practice tmr

49. Group Anagrams
use hashmap to get different size of arrays output practice

438. Find All Anagrams in a String
check sliding winfdow.

not finish
finish two ontest.

Need to study more tmr

463. Island Perimeter

290. Word Pattern

204. Count Primes
practice tmr

30. Substring with Concatenation of All Words
290. Word Pattern
205. Isomorphic Strings
index.put(pattern.charAt(i), i) != index.put(words[i], i) why?

mapc.containsKey(tmpc) ^ mapstr.containsKey(tmpstr)
what does this mean?


!=
Objects.equals(Object a, Object b)
Object.equals(Object o)

// java.util.Objects
public static boolean equals(Object a, Object b) {
     return (a == b) || (a != null && a.equals(b));
}

// java.lang.Object
public boolean equals(Object obj) {
    return (this == obj);
}
246. Strobogrammatic Number
two pointer
try use hashmap tmr

247. Strobogrammatic Number II
recuisive iterative not start yet.
22. Generate Parentheses



补充内容 (2019-10-10 11:33):
public V put(K key,
             V value)
Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced.
Specified by:
put in interface Map<K,V>
Overrides:
put in class AbstractMap<K,V>
Parameters:
key - key with which the specified value is to be associated
value - value to be associated with the specified key
Returns:
the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key.)

204. Count Primes
study more for fasterer solution'

290. Word Pattern
??I have question here, Why my code cannot go through.

205. Isomorphic Strings
done study for more fast solution

30. Substring with Concatenation of All Words
understand try tmr

246. Strobogrammatic Number
understand hashmap
247. Strobogrammatic Number II
understand recursive
389. Find the Difference

409. Longest Palindrome
done.
int [] count = new int[128];
128  these include the digits 0 to 9, lowercase letters a to z, uppercase letters A to Z, and punctuation symbols.
for (int v: count) {
     ans += v / 2 * 2;
     if (ans % 2 == 0 && v % 2 == 1)//this one is nice
     ans++;
        }

Greedy , what is that?
359. Logger Rate Limiter

design
347. Top K Frequent Elements

Heap

30. Substring with Concatenation of All Words
finish one way, need to study faster way


76. Minimum Window Substring

Sliding window

209. Minimum Size Subarray Sum
NOT DONE YET
567. Permutation in String
239. Sliding Window Maximum
632. Smallest Range Covering Elements from K Lists

347. Top K Frequent Elements
finish, need to study more fast way.
192. Word Frequency
215. Kth Largest Element in an Array
finish with one method. Study more about some other method,
451. Sort Characters By Frequency
659. Split Array into Consecutive Subsequences

347. Top K Frequent Elements
Bucket sort, practice tommorrow. Good idea.
Question here: How does this code manage the sequence?

Tree Set
692. Top K Frequent Words
similar to 347
half done: question: how to make sure the out put sequence?
Tree Set
451. Sort Characters By Frequency

周六休息

692. Top K Frequent Words
compareto ？？？
347. Top K Frequent Elements

266. Palindrome Permutation
Approach 4.
deal with odd and even occurence.
similar question.

A set of questions:
Backtracking
267. Palindrome Permutation II
31. Next Permutation
47. Permutations II

Group series:
49. Group Anagrams
question here: return ans.values();
return ArrayList(ans.values());
why?
249. Group Shifted Strings

contest
1217. Play with Chips
1218. Longest Arithmetic Subsequence of Given Difference

Subsequence

692. Top K Frequent Words
compareto ？？？
347. Top K Frequent Elements

266. Palindrome Permutation
Approach 4.
deal with odd and even occurence.
similar question.

A set of questions:
Backtracking
267. Palindrome Permutation II
31. Next Permutation
47. Permutations II

Group series:
49. Group Anagrams
question here: return ans.values();
return ArrayList(ans.values());
why?
249. Group Shifted Strings

contest
1217. Play with Chips
1218. Longest Arithmetic Subsequence of Given Difference

Subsequence