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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.math.BigInteger;
  4.  
  5. class Scratch {
  6.  
  7.     static int compare(String v1, String v2) {
  8.         boolean neg1 = v1.startsWith("-");
  9.         boolean neg2 = v2.startsWith("-");
  10.         return neg1 ? (neg2 ? -comparePositives(v1.substring(1), v2.substring(1)) : -1)
  11.                     : (neg2 ? 1 : comparePositives(v1, v2));
  12.     }
  13.  
  14.     static int comparePositives(String v1, String v2) {
  15.         // Is one longer?
  16.         if (v1.length() != v2.length())
  17.             return v1.length() < v2.length() ? -1 : 1;
  18.  
  19.         // Both empty?
  20.         if (v1.isEmpty())
  21.             return 0;
  22.  
  23.         // First digit differs?
  24.         if (v1.charAt(0) != v2.charAt(0))
  25.             return v1.charAt(0) < v2.charAt(0) ? -1 : 1;
  26.  
  27.         // Recurse on rest of number
  28.         return comparePositives(v1.substring(1), v2.substring(1));
  29.     }
  30.  
  31.     public static void main(String[] args) {
  32.         String[] testCases = {
  33.                 "-4681282181239921821823815829",
  34.                 "-9223372036854775809", // MIN_VALUE-1
  35.                 "" + Long.MIN_VALUE,
  36.                 "-123456",
  37.                 "-55555",
  38.                 "-1",
  39.                 "0",
  40.                 "1",
  41.                 "55555",
  42.                 "123456",
  43.                 "" + Long.MAX_VALUE,
  44.                 "9223372036854775808", // MAX_VALUE+1
  45.                 "-4681282181239921821823815829"
  46.         };
  47.  
  48.         for (String testVal1 : testCases) {
  49.             for (String testVal2 : testCases) {
  50.                 int expected = new BigInteger(testVal1).compareTo(new BigInteger(testVal2));
  51.                 int actual = compare(testVal1, testVal2);
  52.                 System.out.printf("%30s  %30s  %d  %d%n", testVal1, testVal2, expected, actual);
  53.                 if (expected != actual) {
  54.                     System.err.println("    fail");
  55.                     System.err.printf("%30s%n", testVal1);
  56.                     System.err.printf("%30s%n", testVal2);
  57.                 }
  58.             }
  59.         }
  60.     }
  61. }
  62.  
  63.  
Success #stdin #stdout 0.14s 380544KB
comments (?)
stdin 
Standard input is empty
stdout 
 -4681282181239921821823815829   -4681282181239921821823815829  0  0
 -4681282181239921821823815829            -9223372036854775809  -1  -1
 -4681282181239921821823815829            -9223372036854775808  -1  -1
 -4681282181239921821823815829                         -123456  -1  -1
 -4681282181239921821823815829                          -55555  -1  -1
 -4681282181239921821823815829                              -1  -1  -1
 -4681282181239921821823815829                               0  -1  -1
 -4681282181239921821823815829                               1  -1  -1
 -4681282181239921821823815829                           55555  -1  -1
 -4681282181239921821823815829                          123456  -1  -1
 -4681282181239921821823815829             9223372036854775807  -1  -1
 -4681282181239921821823815829             9223372036854775808  -1  -1
 -4681282181239921821823815829   -4681282181239921821823815829  0  0
          -9223372036854775809   -4681282181239921821823815829  1  1
          -9223372036854775809            -9223372036854775809  0  0
          -9223372036854775809            -9223372036854775808  -1  -1
          -9223372036854775809                         -123456  -1  -1
          -9223372036854775809                          -55555  -1  -1
          -9223372036854775809                              -1  -1  -1
          -9223372036854775809                               0  -1  -1
          -9223372036854775809                               1  -1  -1
          -9223372036854775809                           55555  -1  -1
          -9223372036854775809                          123456  -1  -1
          -9223372036854775809             9223372036854775807  -1  -1
          -9223372036854775809             9223372036854775808  -1  -1
          -9223372036854775809   -4681282181239921821823815829  1  1
          -9223372036854775808   -4681282181239921821823815829  1  1
          -9223372036854775808            -9223372036854775809  1  1
          -9223372036854775808            -9223372036854775808  0  0
          -9223372036854775808                         -123456  -1  -1
          -9223372036854775808                          -55555  -1  -1
          -9223372036854775808                              -1  -1  -1
          -9223372036854775808                               0  -1  -1
          -9223372036854775808                               1  -1  -1
          -9223372036854775808                           55555  -1  -1
          -9223372036854775808                          123456  -1  -1
          -9223372036854775808             9223372036854775807  -1  -1
          -9223372036854775808             9223372036854775808  -1  -1
          -9223372036854775808   -4681282181239921821823815829  1  1
                       -123456   -4681282181239921821823815829  1  1
                       -123456            -9223372036854775809  1  1
                       -123456            -9223372036854775808  1  1
                       -123456                         -123456  0  0
                       -123456                          -55555  -1  -1
                       -123456                              -1  -1  -1
                       -123456                               0  -1  -1
                       -123456                               1  -1  -1
                       -123456                           55555  -1  -1
                       -123456                          123456  -1  -1
                       -123456             9223372036854775807  -1  -1
                       -123456             9223372036854775808  -1  -1
                       -123456   -4681282181239921821823815829  1  1
                        -55555   -4681282181239921821823815829  1  1
                        -55555            -9223372036854775809  1  1
                        -55555            -9223372036854775808  1  1
                        -55555                         -123456  1  1
                        -55555                          -55555  0  0
                        -55555                              -1  -1  -1
                        -55555                               0  -1  -1
                        -55555                               1  -1  -1
                        -55555                           55555  -1  -1
                        -55555                          123456  -1  -1
                        -55555             9223372036854775807  -1  -1
                        -55555             9223372036854775808  -1  -1
                        -55555   -4681282181239921821823815829  1  1
                            -1   -4681282181239921821823815829  1  1
                            -1            -9223372036854775809  1  1
                            -1            -9223372036854775808  1  1
                            -1                         -123456  1  1
                            -1                          -55555  1  1
                            -1                              -1  0  0
                            -1                               0  -1  -1
                            -1                               1  -1  -1
                            -1                           55555  -1  -1
                            -1                          123456  -1  -1
                            -1             9223372036854775807  -1  -1
                            -1             9223372036854775808  -1  -1
                            -1   -4681282181239921821823815829  1  1
                             0   -4681282181239921821823815829  1  1
                             0            -9223372036854775809  1  1
                             0            -9223372036854775808  1  1
                             0                         -123456  1  1
                             0                          -55555  1  1
                             0                              -1  1  1
                             0                               0  0  0
                             0                               1  -1  -1
                             0                           55555  -1  -1
                             0                          123456  -1  -1
                             0             9223372036854775807  -1  -1
                             0             9223372036854775808  -1  -1
                             0   -4681282181239921821823815829  1  1
                             1   -4681282181239921821823815829  1  1
                             1            -9223372036854775809  1  1
                             1            -9223372036854775808  1  1
                             1                         -123456  1  1
                             1                          -55555  1  1
                             1                              -1  1  1
                             1                               0  1  1
                             1                               1  0  0
                             1                           55555  -1  -1
                             1                          123456  -1  -1
                             1             9223372036854775807  -1  -1
                             1             9223372036854775808  -1  -1
                             1   -4681282181239921821823815829  1  1
                         55555   -4681282181239921821823815829  1  1
                         55555            -9223372036854775809  1  1
                         55555            -9223372036854775808  1  1
                         55555                         -123456  1  1
                         55555                          -55555  1  1
                         55555                              -1  1  1
                         55555                               0  1  1
                         55555                               1  1  1
                         55555                           55555  0  0
                         55555                          123456  -1  -1
                         55555             9223372036854775807  -1  -1
                         55555             9223372036854775808  -1  -1
                         55555   -4681282181239921821823815829  1  1
                        123456   -4681282181239921821823815829  1  1
                        123456            -9223372036854775809  1  1
                        123456            -9223372036854775808  1  1
                        123456                         -123456  1  1
                        123456                          -55555  1  1
                        123456                              -1  1  1
                        123456                               0  1  1
                        123456                               1  1  1
                        123456                           55555  1  1
                        123456                          123456  0  0
                        123456             9223372036854775807  -1  -1
                        123456             9223372036854775808  -1  -1
                        123456   -4681282181239921821823815829  1  1
           9223372036854775807   -4681282181239921821823815829  1  1
           9223372036854775807            -9223372036854775809  1  1
           9223372036854775807            -9223372036854775808  1  1
           9223372036854775807                         -123456  1  1
           9223372036854775807                          -55555  1  1
           9223372036854775807                              -1  1  1
           9223372036854775807                               0  1  1
           9223372036854775807                               1  1  1
           9223372036854775807                           55555  1  1
           9223372036854775807                          123456  1  1
           9223372036854775807             9223372036854775807  0  0
           9223372036854775807             9223372036854775808  -1  -1
           9223372036854775807   -4681282181239921821823815829  1  1
           9223372036854775808   -4681282181239921821823815829  1  1
           9223372036854775808            -9223372036854775809  1  1
           9223372036854775808            -9223372036854775808  1  1
           9223372036854775808                         -123456  1  1
           9223372036854775808                          -55555  1  1
           9223372036854775808                              -1  1  1
           9223372036854775808                               0  1  1
           9223372036854775808                               1  1  1
           9223372036854775808                           55555  1  1
           9223372036854775808                          123456  1  1
           9223372036854775808             9223372036854775807  1  1
           9223372036854775808             9223372036854775808  0  0
           9223372036854775808   -4681282181239921821823815829  1  1
 -4681282181239921821823815829   -4681282181239921821823815829  0  0
 -4681282181239921821823815829            -9223372036854775809  -1  -1
 -4681282181239921821823815829            -9223372036854775808  -1  -1
 -4681282181239921821823815829                         -123456  -1  -1
 -4681282181239921821823815829                          -55555  -1  -1
 -4681282181239921821823815829                              -1  -1  -1
 -4681282181239921821823815829                               0  -1  -1
 -4681282181239921821823815829                               1  -1  -1
 -4681282181239921821823815829                           55555  -1  -1
 -4681282181239921821823815829                          123456  -1  -1
 -4681282181239921821823815829             9223372036854775807  -1  -1
 -4681282181239921821823815829             9223372036854775808  -1  -1
 -4681282181239921821823815829   -4681282181239921821823815829  0  0
https://ideone.com/HmMkJ3
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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