Design-1/MyHashMap.java at master · Simranb10/Design-1 · GitHub

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//Design a Hash Map
//Time Complexity : Amortized O(1)
//Space Complexity : O(n)

classMyHashMap {

Node[] map;
intbuckets;

privatestaticclassNode {
intkey;
intval;
Nodenext;

publicNode(intkey, intval) {
this.key = key;
this.val = val;
 }
 }

publicMyHashMap() {
this.buckets = 1000;
map = newNode[buckets];
 }

privateNodegetPrevious(Nodehead, intkey) {
Nodeprev = null;
Nodecurr = head;

while(curr != null && curr.key != key) {
prev = curr;
curr = curr.next;
 }
returnprev;
 }

publicvoidput(intkey, intvalue) {
Nodecurr = newNode(key, value);
intindex = key % buckets;
if(map[index] == null) {
map[index] = newNode(-1,-1);
map[index].next = curr;
 }
else {
Nodeprev = getPrevious(map[index], key);
if(prev.next == null) {
prev.next = curr;
 } else {
prev.next.val = value;
 }
 }
 }

publicintget(intkey) {
intindex = key % buckets;
if(map[index] == null)
return -1;
Nodeprev = getPrevious(map[index], key);
if(prev.next == null)
return -1;
returnprev.next.val;
 }

publicvoidremove(intkey) {
intindex = key % buckets;
if(map[index] == null)
return;
Nodeprev = getPrevious(map[index], key);
if(prev.next == null) return;
Nodetemp = prev.next;
prev.next = temp.next;
temp.next = null;
 }
}