leetcode 217

Author: Pankajcoder1

LeetCode/217.Contains_Duplicate.cpp

@@ -0,0 +1,62 @@
+/*
+    written by Pankaj Kumar.
+    country:-INDIA
+*/
+typedef long long ll ;
+
+
+/* ascii value
+A=65,Z=90,a=97,z=122
+*/
+
+/*  --------------------MAIN PROGRAM----------------------------*/
+// to run ctrl+b
+const ll INF=1e18;
+const ll mod1=1e9+7;
+const ll mod2=998244353;
+// Techniques :
+// divide into cases, brute force, pattern finding
+// sort, greedy, binary search, two pointer
+// transform into graph
+
+// Experience :
+// Cp is nothing but only observation and mathematics.
+
+
+//Add main code here
+
+class Solution
+{
+public:
+    bool containsDuplicate(vector<int> &nums)
+    {
+        // approach 1
+        // via map
+        // map<int, int> m;
+        // for (auto x : nums)
+        // {
+        //     m[x]++;
+        //     if (m[x] > 1)
+        //         return true;
+        // }
+        // return false;
+
+        // approach 2
+        // via set
+        set<int> s;
+        for (auto x : nums)
+        {
+            s.insert(x);
+        }
+        return s.size() != nums.size();
+    }
+};
+
+/* -----------------END OF PROGRAM --------------------*/
+/*
+* stuff you should look before submission
+* constraint and time limit
+* int overflow
+* special test case (n=0||n=1||n=2)
+* don't get stuck on one approach if you get wrong answer
+*/