Create minimum-number-of-taps-to-open-to-water-a-garden.cpp

Author: kamyu104

C++/minimum-number-of-taps-to-open-to-water-a-garden.cpp

@@ -0,0 +1,30 @@
+// Time:  O(n)
+// Space: O(n)
+
+class Solution {
+public:
+    int minTaps(int n, vector<int>& ranges) {
+        vector<int> max_range(n + 1);
+        for (int i = 0; i < ranges.size(); ++i) {
+            int left = max(i - ranges[i], 0), right = min(i + ranges[i], n);
+            max_range[left] = max(max_range[left], right - left);
+        }
+        return jumpGame(max_range);
+    }
+
+private:
+    int jumpGame(const vector<int>& A) {
+        int jump_count = 0, reachable = 0, curr_reachable = 0;
+        for (int i = 0; i < A.size(); ++i) {
+            if (i > reachable) {
+                return -1;
+            }
+            if (i > curr_reachable) {
+                curr_reachable = reachable;
+                ++jump_count;
+            }
+            reachable = max(reachable, i + A[i]);
+        }
+        return jump_count;
+    }
+};