From a78c679c0554f9028f3d0e93eb38986ac440ba1d Mon Sep 17 00:00:00 2001
From: Hao Chen <haoel@hotmail.com>
Date: Sun, 9 May 2021 12:42:19 +0800
Subject: [PATCH] New Problem Solution - "1854. Maximum Population Year"

---
 README.md                                     |  1 +
 .../MaximumPopulationYear.cpp                 | 59 +++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 algorithms/cpp/maximumPopulationYear/MaximumPopulationYear.cpp

diff --git a/README.md b/README.md
index 00054326..25c6cacb 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,7 @@ LeetCode
 
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
+|1854|[Maximum Population Year](https://leetcode.com/problems/maximum-population-year/) | [C++](./algorithms/cpp/maximumPopulationYear/MaximumPopulationYear.cpp)|Easy|
 |1851|[Minimum Interval to Include Each Query](https://leetcode.com/problems/minimum-interval-to-include-each-query/) | [C++](./algorithms/cpp/minimumIntervalToIncludeEachQuery/MinimumIntervalToIncludeEachQuery.cpp)|Hard|
 |1850|[Minimum Adjacent Swaps to Reach the Kth Smallest Number](https://leetcode.com/problems/minimum-adjacent-swaps-to-reach-the-kth-smallest-number/) | [C++](./algorithms/cpp/minimumAdjacentSwapsToReachTheKthSmallestNumber/MinimumAdjacentSwapsToReachTheKthSmallestNumber.cpp)|Medium|
 |1849|[Splitting a String Into Descending Consecutive Values](https://leetcode.com/problems/splitting-a-string-into-descending-consecutive-values/) | [C++](./algorithms/cpp/splittingAStringIntoDescendingConsecutiveValues/SplittingAStringIntoDescendingConsecutiveValues.cpp)|Medium|
diff --git a/algorithms/cpp/maximumPopulationYear/MaximumPopulationYear.cpp b/algorithms/cpp/maximumPopulationYear/MaximumPopulationYear.cpp
new file mode 100644
index 00000000..7d9de390
--- /dev/null
+++ b/algorithms/cpp/maximumPopulationYear/MaximumPopulationYear.cpp
@@ -0,0 +1,59 @@
+// Source : https://leetcode.com/problems/maximum-population-year/
+// Author : Hao Chen
+// Date   : 2021-05-09
+
+/***************************************************************************************************** 
+ *
+ * You are given a 2D integer array logs where each logs[i] = [birthi, deathi] indicates the birth and 
+ * death years of the i^th person.
+ * 
+ * The population of some year x is the number of people alive during that year. The i^th person is 
+ * counted in year x's population if x is in the inclusive range [birthi, deathi - 1]. Note that the 
+ * person is not counted in the year that they die.
+ * 
+ * Return the earliest year with the maximum population.
+ * 
+ * Example 1:
+ * 
+ * Input: logs = [[1993,1999],[2000,2010]]
+ * Output: 1993
+ * Explanation: The maximum population is 1, and 1993 is the earliest year with this population.
+ * 
+ * Example 2:
+ * 
+ * Input: logs = [[1950,1961],[1960,1971],[1970,1981]]
+ * Output: 1960
+ * Explanation: 
+ * The maximum population is 2, and it had happened in years 1960 and 1970.
+ * The earlier year between them is 1960.
+ * 
+ * Constraints:
+ * 
+ * 	1 <= logs.length <= 100
+ * 	1950 <= birthi < deathi <= 2050
+ ******************************************************************************************************/
+
+class Solution {
+
+public:
+    int maximumPopulation(vector<vector<int>>& logs) {
+        vector<vector<int>> year;
+        
+        for(auto& log : logs) {
+            year.push_back({log[0], 1});
+            year.push_back({log[1], -1});
+        }
+        sort(year.begin(), year.end());
+        
+        int x = year[0][0];
+        int cnt = 0, max_cnt = 0;
+        for(int i=0; i< year.size(); i++) {
+            cnt += year[i][1];
+            if (max_cnt < cnt) {
+                max_cnt = cnt;
+                x = year[i][0];
+            }
+        }
+        return x;
+    }
+};