Merge pull request #42 from BhavikDhandhalya/patch-1

added find permutation

Author: mailtokartik1

Arrays/Find Permutation.cpp

@@ -0,0 +1,32 @@
+/*
+Solution by : Bhavik Dhandhalya
+Given a positive integer n and a string s consisting only of letters D or I, you have to find any permutation of first n positive integer that satisfy the given input string.
+
+D means the next number is smaller, while I means the next number is greater.
+
+Notes
+Length of given string s will always equal to n - 1
+Your solution should run in linear time and space.
+
+Input 1:
+
+n = 3
+s = ID
+Return: [1, 3, 2]
+
+Solution Complexity : O(N) time and O(1) space
+Refer this URL for lexicographically smaller permutation solution:
+https://leetcode.com/articles/find-permutation/
+*/
+
+vector<int> Solution::findPerm(const string A, int B) {
+    vector < int > ans;
+    int n = A.length();
+    int maxi = n + 1, mini = 1;
+    for (int i = 0; i < n; i++) {
+        if (A[i] == 'I') ans.push_back(mini++);
+        if (A[i] == 'D') ans.push_back(maxi--);
+    }
+    ans.push_back(maxi);
+    return ans;
+}