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:
In the beginning, you have the permutation P=[1,2,3,...,m].
For the current i, find the position of queries[i] in the permutation P (indexing from 0) and then move this at the beginning of the permutation P. Notice that the position of queries[i] in P is the result for queries[i].
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:
1 <= m <= 10^3
1 <= queries.length <= m
1 <= queries[i] <= m
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;
}
}