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refactor 81
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  • src/main/java/com/fishercoder/solutions

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‎src/main/java/com/fishercoder/solutions/_81.java

Lines changed: 39 additions & 157 deletions
Original file line numberDiff line numberDiff line change
@@ -4,171 +4,53 @@
44
* 81. Search in Rotated Sorted Array II
55
*
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* Follow up for "Search in Rotated Sorted Array":
7+
*
78
* What if duplicates are allowed?
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* Would this affect the run-time complexity? How and why?
910
* Write a function to determine if a given target is in the array.
1011
*/
1112
public class _81 {
1213

13-
public static class Solution1 {
14-
public boolean search(int[] A, int target) {
15-
int len = A.length;
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if (len == 0) {
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return false;
18-
}
19-
if (len == 1) {
20-
if (A[0] == target) {
21-
return true;
22-
} else {
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return false;
24-
}
25-
}
26-
int watershed = A[0];
27-
int watershedIndex = 0;
28-
for (int i = 0; i < len - 1; i++) {
29-
if (A[i] > A[i + 1]) {
30-
watershed = A[i];
31-
watershedIndex = i;
32-
System.out.println("Place 1: watershed = " + watershed
33-
+ "\twatershedIndex = " + watershedIndex);
34-
for (int j = i + 1; j < len; j++) {
35-
if (A[j] == A[i]) {
36-
watershed = A[j];
37-
watershedIndex = j;
38-
System.out.println("Place 2: watershed = " + watershed
39-
+ "\twatershedIndex = " + watershedIndex);
40-
} else {
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break;
42-
}
43-
}
44-
}
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}
46-
System.out.println("watershed = " + watershed + "\twatershedIndex = "
47-
+ watershedIndex);
48-
if (target == watershed) {
49-
return true;
50-
} else if (target > watershed) {
51-
/*
52-
* here is the tricky part: when target is greater than watershed,
53-
* it's also possible that this list is ZERO rotated, i.e. it didn't
54-
* rotate at all! Then at this moment, watershed is not the largest
55-
* element int this array, so we need to binary search this whole
56-
* array.
57-
*/
58-
if (watershedIndex == 0) {
59-
int start = 0;
60-
int end = len - 1;
61-
int mid = (start + end) / 2;
62-
while (start <= end) {
63-
if (target > A[mid]) {
64-
start = mid + 1;
65-
mid = (start + end) / 2;
66-
} else if (target < A[mid]) {
67-
end = mid - 1;
68-
mid = (start + end) / 2;
69-
} else if (target == A[mid]) {
70-
return true;
71-
}
72-
}
73-
return false;
74-
} else {
75-
return false;
76-
}
77-
} else if (target < watershed) {
78-
/*
79-
* target could be in either part of this sorted array, then we
80-
* check if target is greater than A[0], if so, then search in the
81-
* first part, if not, then check if it is greater than A[len - 1],
82-
* if so, return -1, if not, search in the second part
83-
*/
84-
85-
if (target == A[0]) {
86-
return true;
87-
} else if (target > A[0]) {
88-
int start = 1;
89-
int end = watershedIndex - 1;
90-
int mid = (start + end) / 2;
91-
while (start <= end) {
92-
if (target > A[mid]) {
93-
start = mid + 1;
94-
mid = (start + end) / 2;
95-
} else if (target < A[mid]) {
96-
end = mid - 1;
97-
mid = (start + end) / 2;
98-
} else if (target == A[mid]) {
99-
return true;
100-
}
101-
}
102-
return false;
103-
} else if (target < A[0]) {
104-
if (target == A[len - 1]) {
105-
return true;
106-
} else if (target > A[len - 1]) {
107-
return false;
108-
} else if (target < A[len - 1]) {
109-
int start = watershedIndex + 1;
110-
int end = len - 2;
111-
int mid = (start + end) / 2;
112-
while (start <= end) {
113-
if (target > A[mid]) {
114-
start = mid + 1;
115-
mid = (start + end) / 2;
116-
} else if (target < A[mid]) {
117-
end = mid - 1;
118-
mid = (start + end) / 2;
119-
} else if (target == A[mid]) {
120-
return true;
121-
}
122-
}
123-
return false;
124-
}
125-
}
126-
}
127-
return false;
14+
public static class Solution1 {
15+
public boolean search(int[] nums, int target) {
16+
int start = 0;
17+
int end = nums.length - 1;
18+
19+
//check each num so we will check start == end
20+
//We always get a sorted part and a half part
21+
//we can check sorted part to decide where to go next
22+
while (start <= end) {
23+
int mid = start + (end - start) / 2;
24+
if (nums[mid] == target) {
25+
return true;
12826
}
129-
}
130-
131-
public static class Solution2 {
132-
public boolean search(int[] nums, int target) {
133-
int start = 0;
134-
int end = nums.length - 1;
135-
136-
//check each num so we will check start == end
137-
//We always get a sorted part and a half part
138-
//we can check sorted part to decide where to go next
139-
while (start <= end) {
140-
int mid = start + (end - start) / 2;
141-
if (nums[mid] == target) {
142-
return true;
143-
}
144-
145-
//if left part is sorted
146-
if (nums[start] < nums[mid]) {
147-
if (target < nums[start] || target > nums[mid]) {
148-
//target is in rotated part
149-
start = mid + 1;
150-
} else {
151-
end = mid - 1;
152-
}
153-
} else if (nums[start] > nums[mid]) {
154-
//right part is rotated
155-
156-
//target is in rotated part
157-
if (target < nums[mid] || target > nums[end]) {
158-
end = mid - 1;
159-
} else {
160-
start = mid + 1;
161-
}
162-
} else {
163-
//duplicates, we know nums[mid] != target, so nums[start] != target
164-
//based on current information, we can only move left pointer to skip one cell
165-
//thus in the worst case, we would have target: 2, and array like 11111111, then
166-
//the running time would be O(n)
167-
start++;
168-
}
169-
}
17027

171-
return false;
28+
//if left part is sorted
29+
if (nums[start] < nums[mid]) {
30+
if (target < nums[start] || target > nums[mid]) {
31+
//target is in rotated part
32+
start = mid + 1;
33+
} else {
34+
end = mid - 1;
35+
}
36+
} else if (nums[start] > nums[mid]) {
37+
//right part is rotated
38+
39+
//target is in rotated part
40+
if (target < nums[mid] || target > nums[end]) {
41+
end = mid - 1;
42+
} else {
43+
start = mid + 1;
44+
}
45+
} else {
46+
//duplicates, we know nums[mid] != target, so nums[start] != target
47+
//based on current information, we can only move left pointer to skip one cell
48+
//thus in the worst case, we would have target: 2, and array like 11111111, then
49+
//the running time would be O(n)
50+
start++;
17251
}
52+
}
53+
return false;
17354
}
55+
}
17456
}

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