From 96fd57157aafe44560c828d6f3c4be3ee4555143 Mon Sep 17 00:00:00 2001
From: Manuel Pineda <manuelpineda@google.com>
Date: Sat, 23 Jan 2021 18:00:18 +0100
Subject: [PATCH] Add problems from Biweekly Contest 44.

---
 .../solution.kt                               | 11 +++++
 .../solution.cc                               | 43 +++++++++++++++++++
 .../solution.cc                               | 15 +++++++
 3 files changed, 69 insertions(+)
 create mode 100644 solved/LeetCode/1732. Find the Highest Altitude/solution.kt
 create mode 100644 solved/LeetCode/1733. Minimum Number of People to Teach/solution.cc
 create mode 100644 solved/LeetCode/1734. Decode XORed Permutation/solution.cc

diff --git a/solved/LeetCode/1732. Find the Highest Altitude/solution.kt b/solved/LeetCode/1732. Find the Highest Altitude/solution.kt
new file mode 100644
index 00000000..e45f70f3
--- /dev/null
+++ b/solved/LeetCode/1732. Find the Highest Altitude/solution.kt	
@@ -0,0 +1,11 @@
+class Solution {
+  fun largestAltitude(gain: IntArray): Int {
+    var cur = 0
+    var best = 0
+    for (i in gain) { 
+      cur += i
+      best = best.coerceAtLeast(cur)
+    }
+    return best
+  }
+}
\ No newline at end of file
diff --git a/solved/LeetCode/1733. Minimum Number of People to Teach/solution.cc b/solved/LeetCode/1733. Minimum Number of People to Teach/solution.cc
new file mode 100644
index 00000000..8e492db6
--- /dev/null
+++ b/solved/LeetCode/1733. Minimum Number of People to Teach/solution.cc	
@@ -0,0 +1,43 @@
+class Solution {
+ public:
+  int minimumTeachings(int n, vector<vector<int>>& languages, vector<vector<int>>& friendships) {
+    memo = vector<vector<int>>(501, vector<int>(501, -1));
+
+    vector<set<int>> lang(languages.size());
+    for (int i = 0; i < languages.size(); i++) {
+      for (auto it : languages[i])  lang[i].insert(it);
+    }
+
+    int best = languages.size();
+    for (int cur = 0; cur < n; cur++) {
+      set<int> toTeach;
+      for (auto& fri : friendships) {
+        assert(fri.size() == 2);
+        if (!CanTalk(fri[0] - 1, fri[1] - 1, languages)) {
+          for (auto person : fri) {
+            if (lang[person - 1].count(cur) == 0) {
+              toTeach.insert(person);
+            }
+          }
+        }
+      }
+      best = min<int>(toTeach.size(), best);
+    }
+    return best;
+  }
+
+ private:
+  bool CanTalk(int a, int b, const vector<vector<int>>& lang) {
+    if (memo[a][b] != -1) return memo[a][b];
+
+    set<int> A(lang[a].begin(), lang[a].end());
+    for (auto it : lang[b]) {
+      if (A.count(it)) {
+        return memo[a][b] = 1;
+      }
+    }
+    return memo[a][b] = 0;
+  }
+
+  vector<vector<int>> memo;
+};
diff --git a/solved/LeetCode/1734. Decode XORed Permutation/solution.cc b/solved/LeetCode/1734. Decode XORed Permutation/solution.cc
new file mode 100644
index 00000000..93e328d4
--- /dev/null
+++ b/solved/LeetCode/1734. Decode XORed Permutation/solution.cc	
@@ -0,0 +1,15 @@
+class Solution {
+ public:
+  vector<int> decode(vector<int>& encoded) {
+    vector<int> ans(encoded.size() + 1);
+    int extra = ((ans.size() + 1) / 2) & 1;
+    for (int i = 1; i < encoded.size(); i+=2) {
+      extra ^= encoded[i];
+    }
+    ans[0] = extra;
+    for (int i = 1; i < ans.size(); i++) {
+      ans[i] = ans[i-1] ^ encoded[i-1];
+    }
+    return ans;
+  }
+};