add: 230221-CN

cpp/2302/230221-CN.cpp

@@ -0,0 +1,41 @@
+#include <vector>
+#include <algorithm>
+#include <cstdio>
+
+/**
+ * 1326. Minimum Number of Taps to Open to Water a Garden
+ *
+ * There is a one-dimensional garden on the x-axis. The garden starts at the point 0 and ends at the point n. (i.e The length of the garden is n).
+ * There are n + 1 taps located at points [0, 1, ..., n] in the garden.
+ * Given an integer n and an integer array ranges of length n + 1 where ranges[i] (0-indexed) means the i-th tap can water the area [i - ranges[i], i + ranges[i]] if it was open.
+ * Return the minimum number of taps that should be open to water the whole garden, If the garden cannot be watered return -1.
+ */
+
+class Solution {
+public:
+	static int minTaps(int n, const std::vector<int>& ranges) {
+		std::vector<int> adv(n + 1, -1);
+		for (int i = 0; i <= n; ++i) {
+			if (!ranges[i])
+				continue;
+			// L, R inclusive
+			int L = std::max(0, i - ranges[i]), R = std::min(n, i + ranges[i]);
+			for (int j = L; j <= R; ++j)
+				adv[j] = std::max(adv[j], R);
+		}
+		int ans = 0;
+		for (int i = 0; i < n; ++ans) {
+			if (adv[i] < i || (i == adv[i] && i < n))
+				return -1;
+			i = adv[i];
+		}
+		return ans;
+	}
+};
+
+int main() {
+	std::printf("%d\n", Solution::minTaps(35, {1,0,4,0,4,1,4,3,1,1,1,2,1,4,0,3,0,3,0,3,0,5,3,0,0,1,2,1,2,4,3,0,1,0,5,2}));
+	std::printf("%d\n", Solution::minTaps(7, {1,2,1,0,2,1,0,1}));
+	std::printf("%d\n", Solution::minTaps(3, {0,0,0,0}));
+	std::printf("%d\n", Solution::minTaps(5, {3,0,1,1,0,0}));
+}

cpp/2302/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2302)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2302 230220-CN.cpp)
+ADD_EXECUTABLE(2302 230221-CN.cpp)