刷题记录帖

438. Find All Anagrams in a String
check sliding winfdow.
how to deal with anagrams?
76. Minimum Window Substring
study tomorrow

76. Minimum Window Substring
done
438. Find All Anagrams in a String
done. prc tmr

76. Minimum Window Substring
char[] ch=t.toCharArray();
time complexity for this one.
code 时间优化：
instead i use t.charAt(index), it is much faster.
check time complexity and solution.
567. Permutation in String
debug, why
209. Minimum Size Subarray Sum
finish two pointer. I did brute force before.
code 优化、
Approach #3 Using Binary search [Accepted]
325. Maximum Size Subarray Sum Equals k
560. Subarray Sum Equals K
brute force done study more tmor
239. Sliding Window Maximum
continue with sliding window
463. Island Perimeter
still not finish

567. Permutation in String
How will you check whether one string is a permutation of another string?
One way is to sort the string and then compare
done.
debug 心得: 有时候表达的和自己想的不是一样的。 有耐心， 确认一下自己写的和想的是不是一样的？
边际条件的case

study more approach

周五 study 155

休息一天，不做了

155. Min Stack
716. Max Stack
design

Sliding window , summary
https://leetcode.com/problems/mi ... -substring-problems
340. Longest Substring with At Most K Distinct Characters
159. Longest Substring with At Most Two Distinct Characters
done

146. LRU Cache
not finish yet.
LinkedHashMap.
Approach 2: Hashmap + DoubleLinkedList
Youtube , how list can achieve that?
844. Backspace String Compare
== -> is a reference comparison, i.e. both objects point to the same memory location
.equals() -> evaluates to the comparison of values in the objects
finish stack method. zong jie ziji kaishi de silu.
continue with two pointer method

682. Baseball Game
done
transform string to Integer.

232. Implement Queue using Stacks
need study more
739. Daily Temperatures
good

739. Daily Temperatures
Arrays.fill(next, Integer.MAX_VALUE);
This method assigns the specified data type value to each element of the specified range of the specified array.

Syntax:
// Makes all elements of a[] equal to "val"
public static void fill(int[] a, int val)

// Makes elements from from_Index (inclusive) to to_Index
// (exclusive) equal to "val"
public static void fill(int[] a, int from_Index, int to_Index, int val)

This method doesn't return any value.
Approach #1: Next Array [Accepted]
Approach #2: Stack [Accepted]

496. Next Greater Element I
find the bug of following code:
class Solution {
    public int[] nextGreaterElement(int[] nums1, int[] nums2) {
        Stack<Integer> stack = new Stack<>();
        HashMap<Integer, Integer> map = new HashMap<>();
        for(int i= nums2.length()-1; i>=0;i--){
            while(!stack.isEmpty() && nums2>stack.peek() ){
                stack.pop();
            }
            int find=stack.isEmpty? -1:stack.peek();
            map.push(nums2[i],find);
            stack.push(nums2[i]);
        }
        for(int k=0; k<nums1.length(); k++){
            int temp = nums1[k];
            nums1[k]=map.get(temp);
        }
        return nums1;
    }
}

503. Next Greater Element II
array.length : length is a final variable applicable for arrays. With the help of length variable, we can obtain the size of the array.
string.length() : length() method is a final variable which is applicable for string objects. length() method returns the number of characters presents in the string.

735. Asteroid Collision
good idea~simulation
605. Can Place Flowers
think about it[/i][/i]

605. Can Place Flowers
play chess

394. Decode String
StringBuilder ans = new StringBuilder();

Character.isDigit(string.charAt(index)) (JavaDoc) will return true if it's a digit
Character.isLetter(string.charAt(index)) (JavaDoc) will return true if it's a letter

Java char to int Example: Get ASCII value
Java char to int Example: Character.getNumericValue()
java using Character.getNumericValue(char) method which returns an integer value.
Java char to int Example: String.valueOf()
returns integer value of specified char value using String.valueOf(char) method.
150. Evaluate Reverse Polish Notation
study it
没有脑子想了，休息
周末也能高效率！！周末早点起床