932. Beautiful Array
An array nums of length n is beautiful if:
- nums is a permutation of the integers in the range [1, n].
- For every 0 <= i < j < n, there is no index k with i < k < j where 2 * nums[k] == nums[i] + nums[j].
Given the integer n, return any beautiful array nums of length n. There will be at least one valid answer for the given n.
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| class Solution {
unordered_map<int, vector<int>> dp;
public:
vector<int> beautifulArray(int n) {
if(n == 1) return {1};
if(dp.count(n)) return dp[n];
auto odd = beautifulArray((n + 1) / 2);
auto even = beautifulArray(n/2);
vector<int> res;
for(auto& o : odd) res.push_back(o * 2 - 1);
for(auto& e : even) res.push_back(e * 2);
return dp[n] = res;
}
};
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