Added files via upload

Author: jdm85kor

Chapter8/HashTable.js.txt

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+function HashTable() {
+  this.table = new Array(137);
+  this.simpleHash = simpleHash;
+  this.betterHash = betterHash;
+  this.showDistro = showDistro;
+  this.put = put;
+  this.get = get;
+  // for linear probing
+  this.values = [];
+}
+
+
+// put for linear probing
+function put(key, data) {
+  var pos = this.betterHash(key);
+  if(this.table[pos] == undefined) {
+    this.table[pos] = key;
+    this.values[pos] = data;
+  }
+  else {
+    while ( this.table[pos] != undefined ) {
+      pos++;
+    }
+    this.table[pos] = key;
+    this.values[pos] = data;
+  }
+}
+
+
+// put for separate chaining
+function put(key, data) {
+  var pos = this.betterHash(key);
+  var index = 0;
+  if (this.table[pos][index] == undefined) {
+    this.table[pos][index] = key;
+    this.table[pos][index+1] = data;
+  }
+  index += 2;
+  else {
+    while ( this.table[pos][index] != undefined) {
+      index += 2;
+    }
+    this.table[pos][index] = key;
+    this.table[pos][index+1] = data;
+  }
+}
+
+// modulo
+function simpleHash( data ) {
+  var total = 0;
+  for (var i = 0 ; i < data.length ; ++i ) {
+    total += data.charCodeAt(i);
+  }
+  print( "Hash value: " + data + " -> " + total );
+  return total % this.table.length;
+}
+
+function betterHash(string) {
+  const H = 37;
+  var total = 0;
+  for (var i=0; i < string.length; ++i) {
+    // Horner's method
+    total += H * total + string.charCodeAt(i);
+  }
+  total = total % this.table.length;
+  if (total < 0) {
+    total += this.table.length-1;
+  }
+  return parseInt(total);
+}
+
+function showDistro() {
+  var n = 0;
+  for( var i = 0 ; i < this.table.length; ++i) {
+    if(this.table[i] != undefined) {
+      print( i + ": " + this.table[i] );
+    }
+  }
+}
+
+function getRandomInt ( min, max) {
+  return Math.floor(Math.random() * (max - min +1)) + min;
+}
+
+function genStruData(arr) {
+  for (var i = 0; i < arr.length; ++i) {
+    var num = "";
+    for (var j = 1 ; j <= 9; ++j ) {
+      num += Math.floor(Math.random() * 10);
+    }
+    num += getRandomInt(50,100);
+    arr[i] = num;
+  }
+}
+
+function buildChains(arr) {
+  for ( var i = 0; i < arr.length; ++i) {
+    arr[i] = new Array();
+  }
+}
+
+
+function inHash(key, arr) {
+  var hash = simpleHash(key, arr);
+  var n = 0;
+  if ( key == arr[hash][n]) {
+    return true;
+  }
+  else {
+    while ( arr[hash][n] != undefined) {
+      if ( arr[hash][n] == key) {
+        return true;
+      }
+      ++n;
+    }
+  }
+  return false;
+}
+
+
+// get for separate chaining
+function get(key) {
+  var index = 0;
+  var hash = this.betterHash(key);
+  if ( this.table[hash][index] = key) {
+    return this.table[hash][index+1];
+  }
+  index += 2;
+  else {
+    while (this.table[hash][index] != key){
+      index += 2;
+    }
+    return this.table[hash][index+1];
+  }
+  return undefined;
+}
+
+// get for linear probing
+function get(key) {
+  var hash = -1;
+  hash = this.betterHash(key);
+  if (hash > -1 ) {
+    for (var i = hash; this.table[hash] != undefined;i++) {
+      if ( this.table[hash] == key) {
+        return this.values[hash];
+      }
+    }
+  }
+  return undefined;
+}
+
+function get(key) {
+  return this.table[this.betterHash(key)];
+}