Lintcode 530. Geohash II

This is a followup question for Geohash.

Convert a Geohash string to latitude and longitude.

Try http://geohash.co/.

Check how to generate geohash on wiki: Geohash or just google it for more details.

Example

Example1

Input: "wx4g0s"`
Output: lat = 39.92706299 and lng = 116.39465332

Example2

Input: "w"
Output: lat = 22.50000000 and lng = 112.50000000

Code (Java):

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public class GeoHash {     /*      * @param geohash: geohash a base32 string      * @return: latitude and longitude a location coordinate pair      */     public double[] decode(String geohash) {         // step1: get binary code         //         String binaryGeoHash = getBinaryGeoHash(geohash);           // step 2: get binary representation of the long and latitude         String[] binaryLongLati = getBinaryLongAndLati(binaryGeoHash);           double longtitude = getLocation(binaryLongLati[0], -180, 180);         double latitude = getLocation(binaryLongLati[1], -90, 90);           double[] ans = new double[2];         ans[0] = latitude;         ans[1] = longtitude;           return ans;     }       private double getLocation(String code, double start, double end) {         double mid = start + (end - start) / 2;         for (int i = 0; i < code.length(); i++) {             if (code.charAt(i) == '0') {                 end = mid;             } else {                 start = mid;             }               mid = start + (end - start) / 2;         }           return mid;     }       private String[] getBinaryLongAndLati(String binaryGeoHash) {         String[] ans = new String[2];         StringBuilder longtitude = new StringBuilder();         StringBuilder latitude = new StringBuilder();           for (int i = 0; i < binaryGeoHash.length(); i += 2) {             longtitude.append(binaryGeoHash.charAt(i));             if (i + 1 < binaryGeoHash.length()) {                 latitude.append(binaryGeoHash.charAt(i + 1));             }         }           ans[0] = longtitude.toString();         ans[1] = latitude.toString();           return ans;     }       private String getBinaryGeoHash(String geohash) {         String dict = "0123456789bcdefghjkmnpqrstuvwxyz";         StringBuilder sb = new StringBuilder();         for (int i = 0; i < geohash.length(); i++) {             int base32 = dict.indexOf(geohash.charAt(i));             sb.append(toBase2(base32));         }           return sb.toString();     }       private String toBase2(int num) {         StringBuilder sb = new StringBuilder();         while (num > 0) {             sb.insert(0, num % 2);             num /= 2;         }                   // pad with zeros         while (sb.length() < 5) {             sb.insert(0, '0');         }           return sb.toString();     } }