add insertion-sort.cpp

Algorithms/Sort/C++/insertion-sort.cpp

@@ -0,0 +1,76 @@
+/*
+    insertion-sort.cpp
+
+    Created by Iran Neto on 20/10/18.
+
+    This code implements the insertion sort algorithm with positive numbers.
+    It works by taking one element, analyzing the vector to define where insert it.
+    To compile you must use g++ or gcc and also set a flag to c++11:
+
+    g++ insertion-sort.c -o exec -std=c++11
+
+    To run: ./exec vectorSize MAX_VALUE
+    Example: ./insertion 10 100
+
+    Extra: Use time command from Unix Operating Systems for efficiency measurements
+
+    Best case: Vector already sorted - O(n)
+    Worst case: Vector is reversed order = O(n²)
+*/
+
+#include <iostream>
+#include <vector>
+#include <cstdlib>
+#include <time.h>
+#include <algorithm>
+
+int MAX_VALUE; //needs to be global
+
+int getParameters(int* N, int* MAX_VALUE, int argc, char* argv[]){
+    //get parameters
+    if(argc == 3){
+        *N = atoi(argv[1]);
+        *MAX_VALUE = atoi(argv[2]);
+        std::cout << "Vector size: "<< *N << std::endl;
+        return 0;
+    }
+    return -1;
+}
+
+int randIt(){ return (std::rand()%MAX_VALUE); }
+
+int main(int argc, char* argv[]){
+    int N, res;
+    srand(time(NULL));
+
+    res = getParameters(&N,&MAX_VALUE,argc,argv);
+    if(res != 0){
+        std::cout << "Specify size and max_value... " << std::endl;
+        std::cout << " ./exec vectorSize MAX_VALUE" << std::endl;
+        exit(1);
+    }
+
+    std::vector<int> vec(N);
+    std::generate(vec.begin(), vec.end(), randIt);
+
+    std::cout << "[";
+    for(auto it: vec){ std::cout << " " << it << " ";}
+    std::cout << "]" << std::endl << " Sorting... " << std::endl;
+
+    /* vector.end() == V[N] - vector last element is in vector.end()-1 */
+    //insertion-sort
+    std::vector<int>::iterator it, it2, temp;
+    for(it = vec.begin(); it != vec.end()-1; ++it){
+        it2 = it + 1;
+        std::cout << &it << "- it: " << *it << " " << &it2 << " - it2: " << *it2 << " - it2-1: " << *(it2-1) << std::endl;
+        while(it2 != vec.begin() && *it2 < *(it2 - 1)){
+            std::swap(*(it2-1),*temp);
+            --it2;
+        }
+    }
+
+    //print it sorted
+    std::cout << "["; 
+    for(auto it: vec){ std::cout << " " << it << " ";}
+    std::cout << "]" << std::endl;
+}