Create Strings of Impurity.cpp

Author: MathProgrammer

Contests/AtCoder Beginner Contest 138/Programs/Strings of Impurity.cpp

@@ -0,0 +1,47 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+int main()
+{
+    string S, T;
+    cin >> S >> T;
+    
+    const int NO_OF_ALPHABETS = 26;
+    vector <vector <int> > locations(NO_OF_ALPHABETS);
+    for(int i = 0; i < S.size(); i++)
+    {
+        locations[S[i] - 'a'].push_back(i);
+    }
+    
+    int no_of_concatenations = 1, matched_prefix = -1;
+    for(int i = 0; i < T.size(); i++)
+    {
+        if(locations[T[i] - 'a'].size() == 0)
+        {
+            cout << "-1\n";
+            
+            return 0;
+        }
+        
+        auto it = upper_bound(locations[T[i] - 'a'].begin(), locations[T[i] - 'a'].end(), matched_prefix);
+        
+        if(it == locations[T[i] - 'a'].end())
+        {
+            no_of_concatenations++;
+            
+            matched_prefix = locations[T[i] - 'a'][0];
+        }
+        else
+        {
+            matched_prefix = *it;
+        }
+    }
+    
+    long long final_length = (no_of_concatenations - 1)*1LL*S.size() + (matched_prefix + 1);
+    cout << final_length << "\n";
+    
+    return 0;
+}