first contest in c++

Author: A-stick-bug

3467. Transform Array by Parity.cpp

@@ -0,0 +1,29 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<int> transformArray(vector<int> &nums) {
+        for (int i = 0; i < nums.size(); i++) {
+            nums[i] &= 1;
+        }
+        sort(nums.begin(), nums.end());
+        return nums;
+    }
+};
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    Solution sol;
+    vector<int> input = {1, 2, 3, 4};
+    vector<int> ans = sol.transformArray(input);
+
+    for (int i: ans) {
+        cout << i << "\n";
+    }
+
+    return 0;
+}

3468. Find the Number of Copy Arrays.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    int countArrays(vector<int> &original, vector <vector<int>> &bounds) {
+        int n = original.size();
+        for (int i = 0; i < n; i++) {
+            bounds[i][0] -= original[i];
+            bounds[i][1] -= original[i];
+        }
+
+        int low = -(1 << 30);
+        int high = 1 << 30;
+        for (int i = 0; i < n; i++) {
+            low = max(low, bounds[i][0]);
+            high = min(high, bounds[i][1]);
+        }
+        return max(0, high - low + 1);
+    }
+};

3469. Find Minimum Cost to Remove Array Elements.cpp

@@ -0,0 +1,47 @@
+// https://leetcode.com/problems/find-minimum-cost-to-remove-array-elements/
+// standard array DP
+// - for each index, we can take one of three elements
+// - the one not taken will be split off from the array, there will be at most
+//   one element that is split off since we take 2 of three each time
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<unordered_map<int, int>> memo;
+
+    int solve(vector<int> &arr, int idx, int extra) {
+        if (idx == arr.size() - 1)
+            return max(arr[idx], extra);
+        if (idx == arr.size())
+            return extra;
+        if (memo[idx].count(extra))
+            return memo[idx][extra];
+
+        int best = 1 << 30;
+        best = min(best, solve(arr, idx + 2, arr[idx + 1]) + max(extra, arr[idx]));
+        best = min(best, solve(arr, idx + 2, extra) + max(arr[idx], arr[idx + 1]));
+        best = min(best, solve(arr, idx + 2, arr[idx]) + max(arr[idx + 1], extra));
+
+        return memo[idx][extra] = best;
+    }
+
+    int minCost(vector<int> &nums) {
+        memo.resize(nums.size() + 2);
+        if (nums.size() < 3)
+            return *max_element(nums.begin(), nums.end());
+
+        return solve(nums, 1, nums[0]);
+    }
+};
+
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+
+    return 0;
+}