Adding code for hashmap

Author: bhavnavarshney

Go/hashing/hashmap.go

@@ -0,0 +1,118 @@
+package hashing
+
+import (
+	"crypto/sha1"
+	"errors"
+	"hash"
+	"strconv"
+)
+
+type Node struct {
+	key   string
+	value interface{}
+}
+
+type HashMap struct {
+	count   int
+	size    int
+	buckets [][]Node
+}
+
+func getHash(s string) int {
+	// hsha2 := sha256.Sum256([]byte(s))
+	// fmt.Println(hsha2)
+	// hashbytes := hsha2.Sum(nil)
+	// var mySlice = []byte{244, 244, 244, 244, 244, 244, 244, 244}
+	// data := binary.BigEndian.Uint64(mySlice)
+	// hash, err := strconv.Atoi(fmt.Sprintf("%s", hsha2))
+	// if err != nil {
+	// 	fmt.Printf("Error in getHash function: %v", err)
+	// 	return -1
+	// }
+	// return hash
+
+	var hashVal hash.Hash
+	hashVal = sha1.New()
+	hashVal.Write([]byte(s))
+
+	var bytes []byte
+
+	bytes = hashVal.Sum(nil)
+	byteToInt, _ := strconv.Atoi(string(bytes))
+	return byteToInt
+}
+
+func (h *HashMap) getIndex(key string) int {
+	hashInt := getHash(key)
+	if hashInt != -1 {
+		return getHash(key) % h.size
+	}
+	return -1
+}
+
+func (h *HashMap) getValue(key string) (*Node, bool) {
+	index := h.getIndex(key)
+	if index == -1 {
+		return nil, false
+	}
+	chain := h.buckets[index]
+
+	for _, node := range chain {
+		if node.key == key {
+			return &node, true
+		}
+	}
+	return nil, false
+}
+
+func (h *HashMap) putValue(key string, value interface{}) bool {
+	index := h.getIndex(key)
+	if index == -1 {
+		return false
+	}
+	chain := h.buckets[index]
+
+	//found := false
+
+	for i := range chain {
+		node := &chain[i]
+		if node.key == key {
+			node.value = value
+			return true
+		}
+	}
+
+	if h.size == h.count {
+		return false
+	}
+
+	node := Node{key: key, value: value}
+	chain = append(chain, node)
+	h.buckets[index] = chain
+	h.count++
+	return true
+}
+
+func createHashMap(expectedSize int) (*HashMap, error) {
+	if expectedSize < 1 {
+		return nil, errors.New("Size of the hashmap cannot be less than 1")
+	}
+	b := make([][]Node, expectedSize)
+	for i := 0; i < expectedSize; i++ {
+		b[i] = make([]Node, 0)
+	}
+	h := &HashMap{
+		count:   0,
+		size:    expectedSize,
+		buckets: b,
+	}
+	return h, nil
+}
+
+func (h *HashMap) getCount() int {
+	return h.count
+}
+
+func (h *HashMap) getsize() int {
+	return h.size
+}

Go/hashing/hashmap_impl.go

@@ -0,0 +1,21 @@
+package hashing
+
+import "fmt"
+
+func TestHashing() {
+	hashmap, err := createHashMap(5)
+	if err != nil {
+		fmt.Printf("Error in creating hashmap. Error:%v", err)
+	}
+
+	done := hashmap.putValue("test", "hashmap")
+	if !done {
+		fmt.Printf("Error adding value in hashmap. Error:%v", err)
+	}
+	fmt.Println(hashmap, done)
+	// value, found := hashmap.getValue("test")
+	// if !found {
+	// 	fmt.Printf("Value not found in hashmap")
+	// }
+	// fmt.Println("Value found:", value.value)
+}

Go/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 
+	"github.com/bhavnavarshney/Algorithms-and-Data-Structures/Go/hashing"
 	"github.com/bhavnavarshney/Algorithms-and-Data-Structures/Go/linkedlist"
 )
 
@@ -35,4 +36,7 @@ func main() {
 	l2.DeleteAtIndex(1)
 	l2.Print("Delete at Index 1") // 5
 
+	fmt.Println("\n******** HASHING *********")
+	hashing.TestHashing()
+
 }