Create find-all-good-indices.cpp

Author: kamyu104

C++/find-all-good-indices.cpp

@@ -0,0 +1,28 @@
+// Time:  O(n)
+// Space: O(n)
+
+// prefix sum
+class Solution {
+public:
+    vector<int> goodIndices(vector<int>& nums, int k) {
+        vector<int> left(size(nums), 1);
+        for (int i = 1; i + 1 < size(nums); ++i) {
+            if (nums[i] <= nums[i - 1]) {
+                left[i] = left[i - 1] + 1;
+            }
+        }
+        vector<int> right(size(nums), 1);
+        for (int i = size(nums) - 2; i >= 1; --i) {
+            if (nums[i] <= nums[i + 1]) {
+                right[i] = right[i + 1] + 1;
+            }
+        }
+        vector<int> result;
+        for (int i = k; i + k < size(nums); ++i) {
+            if (min(left[i - 1], right[i + 1]) >= k) {
+                result.emplace_back(i);
+            }
+        }
+        return result;
+    }
+};