Day-50 Greedy problem + sort problem2

Author: mandliya

README.md

@@ -4,9 +4,9 @@
 
 | Current Status|     Stats     |
 | :------------: | :----------: |
-| Total Problems | 68 |
-| Current Streak | 49 |
-| Longest Streak | 49 ( August 17, 2015 - October 4, 2015 ) |
+| Total Problems | 70 |
+| Current Streak | 50 |
+| Longest Streak | 50 ( August 17, 2015 - October 5, 2015 ) |
 
 </center>
 
@@ -121,10 +121,16 @@ Include contains single header implementation of data structures and some algori
 | Problem | Solution |
 | :------------ | :----------: |
 | Given a sorted vector, return first index of the occurrence of a value in vector, if number does not exist, return -1 | [first_occurrence_binary_search.cpp](sort_search_problems/first_occurrence_binary_search.cpp) |
+| Given a list of unsorted integers, A={a<sub>1</sub>,a<sub>2</sub>,…,a<sub>N</sub>}, Find the pair of elements that have the smallest absolute difference between them? If there are multiple pairs, find them all.| [closest_numbers.cpp](sort_search_problems/closest_numbers.cpp)|
 
 ### Graph Problems
 | Problem | Solution |
 | :------------ | :----------: |
 | Depth First Traversal of a Graph | [dfsDemo.cpp](graph_problems/dfsDemo.cpp) |
 | Breadth First Traversal of a Graph | [bfsDemo.cpp](graph_problems/bfsDemo.cpp) |
 | calculate the shortest distance from the start position (Node S) to all of the other nodes in the graph using Dijkstra algorithm. | [dijkstra-shortest-reach.cpp](graph_problems/dijkstra-shortest-reach.cpp)|
+
+###Greedy Problems
+| Problem | Solution |
+| :------------ | :----------: |
+| Given two integer arrays, A and B, each containing N integers. You are free to permute the order of the elements in the arrays.Is there an permutation A', B' possible of A and B, such that, A'<sub>i</sub>+B'<sub>i</sub> ≥ K for all i, where A'<sub>i<sub> denotes the i<sup>th<sup> element in the array A' and B'<sub>i</sub> denotes i<sup>th</sup> element in the array B'.| [two_arrays.cpp](greedy_problems/two_arrays.cpp)|

greedy_problems/two_arrays.cpp

@@ -0,0 +1,50 @@
+/**
+* Given two array A and B
+* Is there an permutation A', B' possible of A and B, such that, A'i+B'i ≥ K for all i,
+* where A'i denotes the ith element in the array A' and B'i denotes ith element in the array B'.
+*
+* Input: The first line contains two integers, N and K.
+* The second line contains N space separated integers, denoting array A.
+* The third line describes array B in a same format.
+*
+* Output: YES or NO
+*
+* Solution Approach :
+* Greedy Algorithm.
+* sort one of the arrays in ascending order and the other in descending order and
+* then for every i, check if the condition (A[i] + B[i] >= k ) holds true or not
+* for each of the array indices i. It can be deduced that if the condition fails on the sorted arrays,
+* then there exists no permutation of A and B such that the condition holds good.
+*/
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+
+int main() {
+  int N, K;
+  cin >> N >> K;
+  int * A = new int[N];
+  int * B = new int[N];
+  for ( int i = 0; i < N; ++i) {
+    cin >> A[i];
+  }
+  for(int i = 0; i < N; ++i) {
+    cin >> B[i];
+  }
+  sort(A, A + N);
+  sort(B, B + N, std::greater<int>()); //decreasing order sort
+  int j;
+  for( j = 0; j < N; ++j ) {
+    if (A[j] + B[j] < K) {
+      std::cout << "NO" << std::endl;
+      break;
+    }
+  }
+  if ( j == N ) {
+    std::cout << "YES" << std::endl;
+  }
+  return 0;
+}
+

sort_search_problems/closest_nums.cpp

@@ -0,0 +1,42 @@
+/*
+Given a list of unsorted integers, A={a1,a2,…,aN}, Find the pair of elements that have the smallest absolute difference between them? If there are multiple pairs, find them all.
+Input: N= Number of elements, followed by N elements.
+Output: Output the pairs of elements with the smallest difference. If there are multiple pairs, output all of them in ascending order, all on the same line (consecutively) with just a single space between each pair of numbers. If there's a number which lies in two pair, print it two times
+Example:
+    Input : 4
+            5 4 3 2
+    Output: 2 3 3 4 4 5
+*/
+
+#include <iostream>
+#include <vector>
+#include <algorithm>
+#include <climits>
+using namespace std;
+
+
+int main() {
+    int N;
+    vector<int> vec;
+    cin >> N;
+    int x;
+    for ( int i = 0; i < N; ++i) {
+        cin >> x;
+        vec.push_back(x);
+    }
+    sort(vec.begin(), vec.end());
+    int mindiff = INT_MAX;
+    for( size_t i = 0; i < vec.size()-1; ++i){
+        if (vec[i+1]-vec[i] < mindiff) {
+            mindiff = vec[i+1]-vec[i];
+        }
+    }
+    for( size_t i =0; i < vec.size()-1; ++i ) {
+        if (vec[i+1]-vec[i] == mindiff) {
+            std::cout << vec[i] << " " << vec[i+1] << " ";
+        }
+    }
+    std::cout << std::endl;
+    return 0;
+}
+