Queries on a Permutation With Key

Given the array queries of positive integers between 1 and m, you have to process all queries[i] (from i=0 to i=queries.length-1) according to the following rules:

Return an array containing the result for the given queries.

 

Example 1:

Input: queries = [3,1,2,1], m = 5
Output: [2,1,2,1] 
Explanation: The queries are processed as follow: 
For i=0: queries[i]=3, P=[1,2,3,4,5], position of 3 in P is 2, then we move 3 to the beginning of P resulting in P=[3,1,2,4,5]. 
For i=1: queries[i]=1, P=[3,1,2,4,5], position of 1 in P is 1, then we move 1 to the beginning of P resulting in P=[1,3,2,4,5]. 
For i=2: queries[i]=2, P=[1,3,2,4,5], position of 2 in P is 2, then we move 2 to the beginning of P resulting in P=[2,1,3,4,5]. 
For i=3: queries[i]=1, P=[2,1,3,4,5], position of 1 in P is 1, then we move 1 to the beginning of P resulting in P=[1,2,3,4,5]. 
Therefore, the array containing the result is [2,1,2,1].  

Example 2:

Input: queries = [4,1,2,2], m = 4
Output: [3,1,2,0]

Example 3:

Input: queries = [7,5,5,8,3], m = 8
Output: [6,5,0,7,5]

 

Constraints:


Solution:

class Solution {
    public int[] processQueries(int[] queries, int m) {
        LinkedList<Integer> list = new LinkedList();
        for (int i = 1; i <= m; i ++) {
            list.add(i);
        }
        int n = queries.length;
        int[] result = new int[n];
        for (int i = 0; i < n; i ++) {
            int curr = queries[i];
            result[i] = list.indexOf(curr);
            list.remove(result[i]);
            list.addFirst(curr);
        }
        return result;
    }
}

Solution2:

BIT

class Solution {
    class BIT {
        int[] arr;
        
        public BIT(int n) {
            arr = new int[n + 1];
        }
        
        public void update(int i, int val) {
            i ++;
            while (i < arr.length) {
                arr[i] += val;
                i += i & -i;
            }
        }
        
        public int sum(int i) {
            i ++;
            int sum = 0;
            while (i > 0) {
                sum += arr[i];
                i -= i & -i;
            }
            return sum;
        }
    }
    
    public int[] processQueries(int[] queries, int m) {
        int n = queries.length;
        BIT bit = new BIT(m + n + 1);
        Map<Integer, Integer> map = new HashMap();
        for (int i = 1; i <= m; i ++) {
            bit.update(n + i, 1);
            map.put(i, n + i);
        }
        int[] res = new int[n];
        for (int i = 0; i < n; i ++) {
            int index = map.get(queries[i]);
            res[i] = bit.sum(index - 1);
            int newIndex = n - i;
            bit.update(index, -1);
            bit.update(newIndex, 1);
            map.put(queries[i], newIndex);
        }
        return res;
    }
}