Go challenge 3 (YearOfProgramming#427)

* Add solution for max occurance challenge

* Add test cases

* Add README.md

* Move code to correct location

challenge_3/go/makernaren/README.md

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+## Single Number
+#### To run the code : 
+* Open this directory in terminal and run `go run max_occurance.go` to compile and run the code.
+* To test the code just run, `go test` in same directory.
+```
+$ go run max_occurance.go 
+gGiven array is : [2 a l 3 l 4 k 2 3 4 a 6 c 4 m 6 m k 9 10 9 8 7 8 10 7] 
+Element that occur only max number of times : 4
+
+$ go test                
+PASS
+ok      path/to/2017Challenges/challenge_2/rust/makernaren 0.005s
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured
+```

challenge_3/go/makernaren/max_occurance.go

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+// Take an array of mixed data types and find the element that occurs
+// most number of times.
+package main
+
+import (
+	"fmt"
+)
+
+// Finds the maximum occurance, takes in interface as input and output params
+//as elements in the given array may be of any data type
+func FindMajority(input []interface{}) (result interface{}) {
+	// Create a hashmap, where element of that array is key and its number of
+	// occurances is the value.
+	occurances := make(map[interface{}]int)
+	for _, key := range input {
+		occurances[key]++
+	}
+	// Return when we find the max occurance.
+	max := 0
+	kv_pair := make([]interface{}, 2)
+	for k, v := range occurances {
+		// Replace the variable until you find max
+		if v > max {
+			max = v
+			kv_pair[0] = k
+			kv_pair[1] = v
+		}
+	}
+	return kv_pair[0]
+}
+
+func main() {
+	given := []interface{}{2, "a", "l", 3, "l", 4, "k", 2, 3, 4, "a", 6, "c",
+		4, "m", 6, "m", "k", 9, 10, 9, 8, 7, 8, 10, 7}
+	fmt.Printf("Given array is : %v \n", given)
+	result := FindMajority(given)
+	fmt.Printf("Element that occur only max number of times : %v \n", result)
+}

challenge_3/go/makernaren/max_occurance_test.go

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+// max_occurance_test
+package main
+
+import (
+	"testing"
+)
+
+func TestIntegers(t *testing.T) {
+	input := []interface{}{2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 6}
+	output := 4
+	result := FindMajority(input)
+	if result != output {
+		t.Error("for", input,
+			"expected", output,
+			"got", result)
+	}
+}
+
+func TestStrings(t *testing.T) {
+	input := []interface{}{"a", "a", "b", "b", "b", "b", "c", "c", "c", "c",
+		"c", "d", "d", "e"}
+	output := "c"
+	result := FindMajority(input)
+	if result != output {
+		t.Error("for", input,
+			"expected", output,
+			"got", result)
+	}
+}
+
+func TestMultipleTypes(t *testing.T) {
+	input := []interface{}{2, "a", "l", 3, "l", 4, "k", 2, 3, 4, "a", 6, "c",
+		4, "m", 6, "m", "k", 9, 10, 9, 8, 7, 8, 10, 7, 7, 7, 7, 7, 7, 7, 7, 7}
+	output := 7
+	result := FindMajority(input)
+	if result != output {
+		t.Error("for", input,
+			"expected", output,
+			"got", result)
+	}
+}