class Solution {
public int[] getAverages(int[] nums, int k) {
int[] res = new int[nums.length];
int l = 0;
long sum = 0; //不为long 类型的话，最后一个用例会溢出
for (int i = 0; i < nums.length; i++) {
res[i] = -1;
if (i < 2 * k) { //当前窗口大小不够，就向右扩一个
sum += nums[i];
}else {
sum += nums[i];//窗口右扩一个,此时窗口大小刚好
res[i - k] = (int) (sum / (2 * k + 1)); //那么i - k索引处的元素就是在窗口中间，就可以算该处为中心的平均值
sum -= nums[l++];//窗口左边界收缩一个，可以是窗口大小保持为2 * k + 1
}
}
return res;
}
}
class Solution {
public:
vector<int> getAverages(vector<int>& nums, int k) {
int n = nums.size();
vector<int> ans(n, -1);
if (k * 2 + 1 <= n) {
long long sum = accumulate(nums.begin(), nums.begin() + k * 2 + 1, 0LL);
for (int i = k; i + k < n; ++i) {
if (i != k) {
sum += nums[i + k] - nums[i - k - 1];
}
ans[i] = sum / (k * 2 + 1);
}
}
return ans;
}
};
class Solution:
def getAverages(self, nums: List[int], k: int) -> List[int]:
n = len(nums)
ans = [-1] * n
if k * 2 + 1 <= n:
total = sum(nums[:k * 2 + 1])
for i in range(k, n - k):
if i != k:
total += nums[i + k] - nums[i - k - 1]
ans[i] = total // (k * 2 + 1)
return ans
func getAverages(nums []int, k int) []int {
avgs := make([]int, len(nums))
sum := 0
for i, v := range nums {
if i < k || i+k >= len(nums) { // 超过边界
avgs[i] = -1
}
sum += v // 进入窗口
if i >= k*2 {
avgs[i-k] = sum / (k*2+1)
sum -= nums[i-k*2] // 窗口最左边的元素离开窗口
}
}
return avgs
}
