Leetcode in Java && MySQL

2021-12-12 21:40:35 #N557. Reverse Words in a String III
problem link

#solution
class Solution {
public String reverseWords(String s) {
StringBuilder sb = new StringBuilder();
String[] words = s.split(" ");

for(String word: words){
sb.append(" ");

sb.append(new StringBuilder(word).reverse());
}

return sb.toString().trim();
}
} Open / Comment

2021-12-12 21:28:18 #N1941. Check if All Characters Have Equal Number of Occurrences
problem link

#solution
class Solution {
public boolean areOccurrencesEqual(String s) {
int freq[] = new int[26], count=0;
char temp=s.charAt(0);

for(char ch: s.toCharArray()){
if(ch == temp) count++;
freq[ch-'a']++;
}

for(int i: freq)
if(i != 0 && i != count) return false;

return true;
}
} Open / Comment

2021-12-12 09:57:07 #statistics
Till this time, 192 in total,
180 easy;
12 medium;
type of problem solutions have been posted Open / Comment

2021-12-10 00:07:41 #N1374. Generate a String With Characters That Have Odd Counts
problem link

#solution
class Solution {
public String generateTheString(int n) {
StringBuilder sb = new StringBuilder();

for(int i=0; i sb.append('a');

return (n%2==0)?sb.append('b').toString():sb.append('a').toString();
}
}

25 views𝐉𝐚𝐤𝐡𝐨𝐧𝐠𝐢𝐫, 21:07

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2021-12-10 00:00:53 #N1436. Destination City
problem link

#solution
class Solution {
public String destCity(List> paths) {
Map map = new HashMap<>();

for(List list: paths){
map.put(list.get(0), map.getOrDefault(list.get(0), 0) -1);
map.put(list.get(1), map.getOrDefault(list.get(1), 0) +1);
}

for(Map.Entry entry: map.entrySet())
if(entry.getValue()>0) return entry.getKey();

return new String();
}
}

22 views𝐉𝐚𝐤𝐡𝐨𝐧𝐠𝐢𝐫, 21:00

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2021-12-09 23:53:42 #N1370. Increasing Decreasing String
problem link

#solution
class Solution {
public String sortString(String s) {
int count[] = new int[26];
StringBuilder sb=new StringBuilder();
for(char ch: s.toCharArray())
count[ch-'a']++;

while(sb.toString().length() for(int i=0; i<26; i++){
if(count[i]>0){
sb.append((char) (i+'a'));
count[i]--;
}
}

for(int i=25; i>=0; i--){
if(count[i]>0){
sb.append((char) (i+'a'));
count[i]--;
}
}
}

return sb.toString();
}
}

12 views𝐉𝐚𝐤𝐡𝐨𝐧𝐠𝐢𝐫, 20:53

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2021-12-09 23:23:48 #N167. Two Sum II - Input Array Is Sorted
problem link

#solution
class Solution {
public int[] twoSum(int[] numbers, int target) {
int start = 0, end = numbers.length - 1;
while(start < end){
if(numbers[start] + numbers[end] == target) break;
if(numbers[start] + numbers[end] < target) start++;
else end--;
}
return new int[]{start + 1, end + 1};
}
} Open / Comment

2021-12-09 23:22:29 #N1560. Most Visited Sector in a Circular Track
problem link

#solution
class Solution {
public List mostVisited(int n, int[] rounds) {
int l=rounds.length;
List list = new ArrayList<>();

for(int i=rounds[0]; i<=rounds[l-1]; i++)
list.add(i);

if(list.size()>0) return list;

for(int i=1; i<=rounds[l-1]; i++)
list.add(i);
for(int i=rounds[0]; i<=n; i++)
list.add(i);

return list;
}
}

12 views𝐉𝐚𝐤𝐡𝐨𝐧𝐠𝐢𝐫, 20:22

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2021-12-09 22:46:21 #N1331. Rank Transform of an Array
problem link

#solution
class Solution {
public int[] arrayRankTransform(int[] arr) {
int[] helper = Arrays.copyOf(arr, arr.length);
Arrays.sort(helper);
Map rank = new HashMap<>();
int pos=1;
for(int n: helper)
if(rank.getOrDefault(n, 0) == 0) rank.put(n, rank.size()+1);

for(int i=0; i arr[i] = rank.get(arr[i]);

return arr;
}
}

13 views𝐉𝐚𝐤𝐡𝐨𝐧𝐠𝐢𝐫, 19:46

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2021-12-09 22:31:00 #N896. Monotonic Array
problem link

#solution
class Solution {
public boolean isMonotonic(int[] nums) {
int countI=0, countD=0, l=nums.length;
for(int i=0; i if(nums[i] == nums[i+1]){
countI++;
countD++;
}
else if(nums[i] < nums[i+1]) countI++;
else countD++;
}

return countI == l-1 || countD == l-1;
}
}

14 views𝐉𝐚𝐤𝐡𝐨𝐧𝐠𝐢𝐫, edited  19:31

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