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The Leetcode
The Leetcode
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‎AddBinary.java

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package Algorithms;
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public class AddBinary {
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public static void main(String[] args) {
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AddBinary ab = new AddBinary();
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System.out.println(ab.addBinary("100", "110010"));
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return;
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}
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public String addBinary(String a, String b) {
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int sLen = 0;
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int lLen = 0;
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int carries = 0;
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String l = null;
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String s = null;
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if (a.length() > b.length()) {
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sLen = b.length();
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lLen = a.length();
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l = a;
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s = b;
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} else {
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sLen = a.length();
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lLen = b.length();
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l = b;
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s = a;
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}
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StringBuilder rst = new StringBuilder();
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int i = 0;
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for (i = sLen - 1; i >= 0; i--) {
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int sum = (int)(s.charAt(i) - '0') + (int)(l.charAt(lLen - sLen + i) - '0') + carries;
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if (sum >= 2) {
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carries = 1;
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} else {
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carries = 0;
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}
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rst.insert(0, String.valueOf(sum%2));
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}
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for (i = lLen - sLen - 1; i >= 0; i--) {
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if (carries == 1) {
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if (l.charAt(i) == '0') {
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carries = 0;
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rst.insert(0,'1');
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} else {
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rst.insert(0,'0');
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}
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} else {
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rst.insert(0, l, 0, i + 1);
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return rst.toString();
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}
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}
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if (carries == 1) {
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rst.insert(0,'1');
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}
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return rst.toString();
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}
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}

‎Ag.java

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package Algorithms;
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abstract public class Ag {
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}

‎Anagrams.java

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package Algorithms;
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import java.util.ArrayList;
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import java.util.HashMap;
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public class Anagrams {
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public static void main(String[] args) {
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Anagrams an = new Anagrams();
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String[] strs = {"car","dog","god","rac","mon","bac","acr","mea","cab", "abd", "adb"};
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//String[] strs = {"abc", "bac"};
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System.out.println(an.anagrams(strs).toString());
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}
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private int getHash(int[] count) {
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int hash = 0;
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int a = 378551;
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int b = 63689;
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// int a = 777877;
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// int b = 123451;
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for (int num : count) {
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hash = hash * a + num;
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a = a * b;
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}
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return hash;
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}
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public ArrayList<String> anagrams(String[] strs) {
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ArrayList<String> result = new ArrayList<String>();
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HashMap<Integer, ArrayList<String>> map = new HashMap<Integer, ArrayList<String>>();
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for (String str : strs) {
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int[] count = new int[26];
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for (int i = 0; i < str.length(); i++) {
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count[str.charAt(i) - 'a']++;
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}
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int hash = getHash(count);
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if (!map.containsKey(hash)) {
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map.put(hash, new ArrayList<String>());
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}
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map.get(hash).add(str);
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}
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for (ArrayList<String> tmp : map.values()) {
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if (tmp.size() > 1) {
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result.addAll(tmp);
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}
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}
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return result;
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}
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}

‎BinarySearch.java

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package Algorithms;
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public class BinarySearch {
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public static void main(String[] strs) {
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BinarySearch bs = new BinarySearch();
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int[] num = new int[]{0,1,2,3,4,5};
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int target = 9;
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System.out.print(bs.binarySearch(num, target));
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//int[] num2 = new int[0];
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//System.out.print(bs.binarySearch(num2, target));
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}
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public int binarySearch(int num[], int target) {
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if (num == null || num.length == 0) {
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return -1;
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}
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int left = 0;
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int right = num.length - 1;
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String test = "test";
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String t2 = test.substring(0,0);
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System.out.printf(test.substring(0,0));
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// while (left <= right) {
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// int mid = left + (right - left)/2;
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// if (num[mid] > target) {
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// right = mid - 1;
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// } else if (num[mid] < target) {
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// left = mid + 1;
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// } else {
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// return mid;
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// }
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// }
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// [1, 2]
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while (left + 1 < right) {
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int mid = left + (right - left)/2;
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if (num[mid] > target) {
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right = mid;
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} else if (num[mid] < target) {
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left = mid;
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} else {
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return mid;
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}
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}
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if (num[left] == target) {
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return left;
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} else if (num[right] == target) {
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return right;
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}
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return -1;
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}
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}

‎Combination2.java

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package Algorithms;
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import java.util.ArrayList;
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import java.util.Arrays;
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public class Combination2 {
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public static void main(String[] args) {
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ArrayList<Character> test = new ArrayList<Character>();
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test.add('c');
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test.add('b');
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System.out.printf("Result: %s", test.toString());
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Combination2 cb = new Combination2();
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int[] num = {2,2,2};
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cb.combinationSum2(num, 4);
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}
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public ArrayList<ArrayList<Integer>> combinationSum2(int[] num, int target) {
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// first we should sort the array.
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Arrays.sort(num);
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ArrayList<ArrayList<Integer>> rst = new ArrayList<ArrayList<Integer>>();
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ArrayList<Integer> path = new ArrayList<Integer>();
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cmbHelp(num, 0, path, rst, target);
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return rst;
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}
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public void cmbHelp(int[] num, int index, ArrayList<Integer> path, ArrayList<ArrayList<Integer>> rst, int target) {
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if (target == 0) {
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// add the current set into the result.
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rst.add(new ArrayList<Integer>(path));
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}
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for (int i = index; i < num.length; i++) {
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if (num[i] > target) {
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// don't need to add new element;
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return;
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}
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if (i >= 1 &&
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num[i] == num[i - 1] &&
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(path.size() == 0 || path.get(path.size() - 1) != num[i])) {
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continue;
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}
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path.add(num[i]);
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cmbHelp(num, i + 1, path, rst, target - num[i]);
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path.remove(path.size() - 1);
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}
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return;
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}
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}

‎CombinationSum.java

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package Algorithms;
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import java.util.ArrayList;
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import java.util.Arrays;
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public class CombinationSum{
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public ArrayList<ArrayList<Integer>> combine(int n, int k) {
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ArrayList<ArrayList<Integer>> rst = new ArrayList<ArrayList<Integer>>();
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help(n, 0, new ArrayList<Integer>(), rst, k);
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return rst;
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}
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public void help(int n, int index, ArrayList<Integer> path, ArrayList<ArrayList<Integer>> rst, int k) {
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if (path.size() == k) {
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rst.add(new ArrayList<Integer>(path));
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return;
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}
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for (int i = index; i < n; i++) {
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path.add(i + 1);
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help(n, i + 1, path, rst, k);
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path.remove(path.size() - 1);
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}
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return;
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}
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public static void main(String[] args) {
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CombinationSum cs = new CombinationSum();
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int[] num = {1,2};
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cs.combine(1, 1);
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}
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public ArrayList<ArrayList<Integer>> combinationSum(int[] candidates, int target) {
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ArrayList<ArrayList<Integer>> rst = new ArrayList<ArrayList<Integer>> ();
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Arrays.sort(candidates);
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help(candidates, 0, new ArrayList<Integer>(), rst, target);
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System.out.printf(rst.toString());
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return rst;
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}
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public void help(int[] cand, int index, ArrayList<Integer> path, ArrayList<ArrayList<Integer>> rst, int target) {
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if (target == 0) {
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// add the current set into the result.
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rst.add(new ArrayList<Integer>(path));
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return;
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}
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int pre = -1;
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for (int i = index; i < cand.length; i++) {
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if (cand[i] > target) {
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// because the sequence is ascending, so we don't need to go on.
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break;
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}
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if (cand[i] == pre)
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path.add(cand[i]);
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help(cand, index, path, rst, target - cand[i]);
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path.remove(path.size() - 1);
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}
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return;
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}
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}

‎DivideTwoIntegers.java

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package Algorithms;
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public class DivideTwoIntegers {
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public static void main(String[] args) {
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System.out.println(divide(-2147483648, 1));
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}
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public static int divide(int dividend, int divisor) {
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long a = Math.abs((long)dividend);
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long b = Math.abs((long)divisor);
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int ret = 0;
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while (a >= b) {
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long bTmp = b;
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int cnt = 1;
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for (int i = 1; a >= bTmp; cnt <<= 1, bTmp <<= 1) {
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a -= bTmp;
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ret += cnt;
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}
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}
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return ((dividend > 0) ^ (divisor > 0)) ? -ret: ret;
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}
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}

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