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Commitd5335de

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refactor 201
1 parent7606fbd commitd5335de

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2 files changed

+27
-42
lines changed

2 files changed

+27
-42
lines changed
Lines changed: 9 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -1,19 +1,5 @@
11
packagecom.fishercoder.solutions;
22

3-
/**
4-
* 201. Bitwise AND of Numbers Range
5-
*
6-
* Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive.
7-
*
8-
* Example 1:
9-
* Input: [5,7]
10-
* Output: 4
11-
*
12-
* Example 2:
13-
* Input: [0,1]
14-
* Output: 0
15-
*
16-
*/
173
publicclass_201 {
184

195
publicstaticclassSolution1 {
@@ -22,15 +8,17 @@ public static class Solution1 {
228
* Bitwise AND operation within range actually turns out to be doing some operations with just these two boundary numbers: m and n
239
* e.g. 5 and 7, in binary, they are 101 and 111, the result for [5,7] is 5&6&7 which is 101&110&111
2410
* this we can understand it to be shifting the digits of m and n from left to right until they become the same, then we pad that number with zeroes on the right side
11+
* <p>
12+
* A more visual explanation here: https://leetcode.com/problems/bitwise-and-of-numbers-range/solution/
2513
*/
26-
publicintrangeBitwiseAnd(intm,intn) {
27-
inti =0;
28-
while (m !=n) {
29-
m >>=1;
30-
n >>=1;
31-
i++;
14+
publicintrangeBitwiseAnd(intleft,intright) {
15+
intshift =0;
16+
while (left !=right) {
17+
left >>=1;
18+
right >>=1;
19+
shift++;
3220
}
33-
return(n <<i);
21+
returnright <<shift;
3422
}
3523
}
3624
}

‎src/test/java/com/fishercoder/_201Test.java

Lines changed: 18 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -6,13 +6,10 @@
66

77
importstaticorg.junit.Assert.assertEquals;
88

9-
/**
10-
* Created by fishercoder on 5/3/17.
11-
*/
129
publicclass_201Test {
1310
privatestatic_201.Solution1solution1;
14-
privatestaticintm;
15-
privatestaticintn;
11+
privatestaticintleft;
12+
privatestaticintright;
1613
privatestaticintactual;
1714
privatestaticintexpected;
1815

@@ -23,45 +20,45 @@ public static void setup() {
2320

2421
@Test
2522
publicvoidtest1() {
26-
m =5;
27-
n =7;
28-
actual =solution1.rangeBitwiseAnd(m,n);
23+
left =5;
24+
right =7;
25+
actual =solution1.rangeBitwiseAnd(left,right);
2926
expected =4;
3027
assertEquals(expected,actual);
31-
actual =solution1.rangeBitwiseAnd(m,n);
28+
actual =solution1.rangeBitwiseAnd(left,right);
3229
assertEquals(expected,actual);
3330
}
3431

3532
@Test
3633
publicvoidtest2() {
37-
m =1;
38-
n =2;
39-
actual =solution1.rangeBitwiseAnd(m,n);
34+
left =1;
35+
right =2;
36+
actual =solution1.rangeBitwiseAnd(left,right);
4037
expected =0;
4138
assertEquals(expected,actual);
42-
actual =solution1.rangeBitwiseAnd(m,n);
39+
actual =solution1.rangeBitwiseAnd(left,right);
4340
assertEquals(expected,actual);
4441
}
4542

4643
@Test
4744
publicvoidtest3() {
48-
m =0;
49-
n =2147483647;
50-
actual =solution1.rangeBitwiseAnd(m,n);
45+
left =0;
46+
right =2147483647;
47+
actual =solution1.rangeBitwiseAnd(left,right);
5148
expected =0;
5249
assertEquals(expected,actual);
53-
actual =solution1.rangeBitwiseAnd(m,n);
50+
actual =solution1.rangeBitwiseAnd(left,right);
5451
assertEquals(expected,actual);
5552
}
5653

5754
@Test
5855
publicvoidtest4() {
59-
m =20000;
60-
n =2147483647;
61-
actual =solution1.rangeBitwiseAnd(m,n);
56+
left =20000;
57+
right =2147483647;
58+
actual =solution1.rangeBitwiseAnd(left,right);
6259
expected =0;
6360
assertEquals(expected,actual);
64-
actual =solution1.rangeBitwiseAnd(m,n);
61+
actual =solution1.rangeBitwiseAnd(left,right);
6562
assertEquals(expected,actual);
6663
}
6764
}

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