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-rw-r--r--other/k_radius_subarr.cpp45
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diff --git a/other/k_radius_subarr.cpp b/other/k_radius_subarr.cpp
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+// 2090. K Radius Subarray Averages
+#include "leetcode.h"
+
+/*
+ * given a 0-indexed array 'nums' of 'n' integers, and an integer 'k'. the
+ * k-radius average for a subarray of 'nums' centered at some index 'i' with the
+ * radius 'k' is the average of all elements in 'nums' between the indices 'i -
+ * k' and 'i + k' (inclusive). if there are less than 'k' elements before or
+ * after the index 'i', then the k-radius average is -1. build and return 'avgs'
+ * of length 'n' where 'avgs[i]' is the k-radius average for the subarray
+ * centered at index 'i'. the average of 'x' elements is the sum of the 'x'
+ * elements divided by 'x', using integer division. the integer division
+ * truncates toward zero, which means losing its fractional part.
+ */
+
+class Solution {
+public:
+ vector<int> getAverages(vector<int> &nums, int k) {
+ vector<int> ans(nums.size(), -1);
+ long long sum = 0, d = k * 2 + 1;
+ for (int i = 0; i < nums.size(); ++i) {
+ sum += nums[i];
+ if (i + 1 >= d) {
+ if (i >= d)
+ sum -= nums[i - d];
+ ans[i - d / 2] = sum / d;
+ }
+ }
+ return ans;
+ }
+};
+
+int main() {
+ Solution obj;
+ vector<int> n1 = {7, 4, 3, 9, 1, 8, 5, 2, 6}, n2 = {100000}, n3 = {8};
+ for (auto i : obj.getAverages(n1, 3))
+ printf("%d ", i); // expect: -1,-1,-1,5,4,4,-1,-1,-1
+ printf("\n");
+ for (auto i : obj.getAverages(n2, 0))
+ printf("%d ", i); // expect: 100000
+ printf("\n");
+ for (auto i : obj.getAverages(n3, 100000))
+ printf("%d ", i); // expect: -1
+ printf("\n");
+}