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Java Solution for LeetCode algorithm problems, continually updating
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package g0901_1000.s0932_beautiful_array;
// #Medium #Array #Math #Divide_and_Conquer #2022_03_30_Time_1_ms_(89.66%)_Space_43_MB_(38.97%)
import java.util.HashMap;
import java.util.Map;
public class Solution {
private Map memo;
public int[] beautifulArray(int n) {
memo = new HashMap<>();
return helper(n);
}
private int[] helper(int n) {
if (n == 1) {
memo.put(1, new int[] {1});
return new int[] {1};
}
if (memo.containsKey(n)) {
return memo.get(n);
}
int mid = (n + 1) / 2;
int[] left = helper(mid);
int[] right = helper(n - mid);
int[] rst = new int[n];
for (int i = 0; i < mid; i++) {
rst[i] = left[i] * 2 - 1;
}
for (int i = mid; i < n; i++) {
rst[i] = right[i - mid] * 2;
}
memo.put(n, rst);
return rst;
}
}