add: 220115

2201/220115.cpp

@@ -0,0 +1,95 @@
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+#include <cstring>
+
+/**
+ * 1345. Jump Game IV
+ * Given an array of integers arr, you are initially positioned at the first index of the array.
+ * In one step you can jump from index i to index:
+ * i + 1 where: i + 1 < arr.length.
+ * i - 1 where: i - 1 >= 0.
+ * j where: arr[i] == arr[j] and i != j.
+ * Return the minimum number of steps to reach the last index of the array.
+ * Notice that you can not jump outside of the array at any time.
+ */
+
+class Solution {
+private:
+	inline static int dp[50005];
+public:
+	static auto minJumps(const std::vector<int>& arr) {
+		int n = arr.size();
+		std::unordered_map<int, std::vector<int>> m;
+		for (int i = 0; i < n; ++i) {
+			if (m.count(arr[i]))
+				m[arr[i]].push_back(i);
+			else
+				m[arr[i]] = {i};
+		}
+		std::memset(dp, 0x3F, sizeof(int) * n);
+		dp[0] = 0;
+
+		if (m.size() > n / 3) {
+			while (true) {
+				int cnt = 0;
+				for (int i = 1; i < n; ++i) {
+					if (dp[i] > dp[i - 1] + 1) {
+						++cnt;
+						dp[i] = dp[i - 1] + 1;
+					}
+					if (i + 1 < n && dp[i] > dp[i + 1] + 1) {
+						++cnt;
+						dp[i] = dp[i + 1] + 1;
+					}
+					for (int j : m[arr[i]]) {
+						if (dp[i] > dp[j] + 1) {
+							++cnt;
+							dp[i] = dp[j] + 1;
+						}
+					}
+				}
+				if (!cnt)
+					break;
+			}
+		} else {
+			while (true) {
+				int cnt = 0;
+				for (const auto& i : m) {
+					int min = 0x3FFFFFFF;
+					for (const auto& j : i.second) {
+						if (j - 1 >= 0 && dp[j] > 1 + dp[j - 1]) {
+							dp[j] = 1 + dp[j - 1];
+							++cnt;
+						}
+						if (j + 1 < n && dp[j] > 1 + dp[j + 1]) {
+							dp[j] = 1 + dp[j + 1];
+							++cnt;
+						}
+						min = std::min(dp[j], min);
+					}
+					for (const auto& j : i.second) {
+						if (min + 1 < dp[j]) {
+							dp[j] = min + 1;
+							++cnt;
+						}
+					}
+				}
+				if (!cnt)
+					break;
+			}
+		}
+		return dp[n - 1];
+	}
+};
+
+int main() {
+	// {100, -23, -23, 404, 100, 23, 23, 23, 3, 404}
+	// {7, 6, 9, 6, 9, 6, 9, 7}
+	std::vector<int> num;
+	num.reserve(50000);
+	for (int i = 0; i < 50000; ++i)
+		num.push_back(7);
+	std::cout << Solution::minJumps(num);
+	return 0;
+}

2201/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2201)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2201 220115-CN.cpp)
+ADD_EXECUTABLE(2201 220115.cpp)