Leetcode in Java

Character

Obtain Integer from char

1char c = string.charAt(i);
2int  num = c - '0';

Increment a character

1char x='A';
2x=x+1;
3System.out.println(x);

String

Remove last character from string builder

1StringBuilder builder = new StringBuilder();
2builder.deleteCharAt(builder.length() - 1);

PriorityQueue

Ordering a priorityqueue based on value in hashmap

1public int[] topKFrequent(int[] nums, int k) {
2    Map<Integer, Integer> map = new HashMap<>();
3    for (int i = 0; i < nums.length; i++) {
4        map.put(nums[i], map.getOrDefault(nums[i], 0) + 1);
5    }
6    PriorityQueue<Integer> queue = new PriorityQueue<>((a, b) -> {
7        return map.get(b) - map.get(a);
8    });
9    queue.addAll(map.keySet());
10    
11    int[] arr = new int[k];
12    for (int i = 0; i < k; i++) {
13        arr[i] = queue.poll();
14    }
15    return arr;
16}