[Leetcode] 667. Beautiful Arrangement II 解题报告
2018-01-29 10:56
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题目:
Given two integers
you need to construct a list which contains
obeys the following requirement:
Suppose this list is [a1, a2, a3,
... , an], then the list [|a1 -
a2|, |a2 - a3|,
|a3 - a4|, ... , |an-1 -
an|] has exactly
integers.
If there are multiple answers, print any of them.
Example 1:
Example 2:
Note:
The
in the range 1 <= k < n <= 104.
思路:
如果我们需要相邻两数的差距包括1,2, ..., k + 1 (<= n)个数,那么可以采用的策略是让这n个数的排列为:1,k+1,2,k,3,k-1,...。这样它们之间的差距就是k,k-1,k-2,..., 2,1,然后在后面追加其余的数即可。按照这个思路,我们可以写出如下的代码。
代码:
class Solution {
public:
vector<int> constructArray(int n, int k) {
int left = 1, right = k + 1;
vector<int> ans;
while (left <= right) {
ans.push_back(left++);
if (left <= right) {
ans.push_back(right--);
}
}
for (int i = k + 2; i <= n; ++i) {
ans.push_back(i);
}
return ans;
}
};
Given two integers
nand
k,
you need to construct a list which contains
ndifferent positive integers ranging from
1to
nand
obeys the following requirement:
Suppose this list is [a1, a2, a3,
... , an], then the list [|a1 -
a2|, |a2 - a3|,
|a3 - a4|, ... , |an-1 -
an|] has exactly
kdistinct
integers.
If there are multiple answers, print any of them.
Example 1:
Input: n = 3, k = 1 Output: [1, 2, 3] Explanation: The [1, 2, 3] has three different positive integers ranging from 1 to 3, and the [1, 1] has exactly 1 distinct integer: 1.
Example 2:
Input: n = 3, k = 2 Output: [1, 3, 2] Explanation: The [1, 3, 2] has three different positive integers ranging from 1 to 3, and the [2, 1] has exactly 2 distinct integers: 1 and 2.
Note:
The
nand
kare
in the range 1 <= k < n <= 104.
思路:
如果我们需要相邻两数的差距包括1,2, ..., k + 1 (<= n)个数,那么可以采用的策略是让这n个数的排列为:1,k+1,2,k,3,k-1,...。这样它们之间的差距就是k,k-1,k-2,..., 2,1,然后在后面追加其余的数即可。按照这个思路,我们可以写出如下的代码。
代码:
class Solution {
public:
vector<int> constructArray(int n, int k) {
int left = 1, right = k + 1;
vector<int> ans;
while (left <= right) {
ans.push_back(left++);
if (left <= right) {
ans.push_back(right--);
}
}
for (int i = k + 2; i <= n; ++i) {
ans.push_back(i);
}
return ans;
}
};
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