1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
| public class Apple {
public static class TreeNode {
int val;
TreeNode left;
TreeNode right;
public TreeNode(int val) {
this.val = val;
}
}
public static void main(String[] args) {
TreeNode root = new TreeNode(0);
TreeNode n1 = new TreeNode(1);
TreeNode n2 = new TreeNode(2);
TreeNode n3 = new TreeNode(3);
TreeNode n4 = new TreeNode(4);
TreeNode n5 = new TreeNode(5);
TreeNode n6 = new TreeNode(6);
TreeNode n7 = new TreeNode(7);
root.left = n1;
root.right = n2;
n1.left = n5;
n1.right = n6;
n2.left = n3;
n2.right = n4;
n3.left = n7;
System.out.println(findPathBetween(root, n2, n5));
}
public boolean workBreak(String s, List<String> wordDict) {
if (s == null || s.length() == 0 || wordDict == null || wordDict.size() == 0) {
return false;
}
Set<String> wordSet = new HashSet<>();
int maxLen = 0;
for (String word: wordDict) {
wordSet.add(word);
maxLen = Math.max(maxLen, word.length());
}
boolean[] dp = new boolean [s.length() + 1];
for (int i = 1; i <= s.length(); i++) {
for (int j = i - 1; j >= 0 && i - j <= maxLen; j--) {
if (dp[j] && wordSet.contains(s.substring(j, i))) {
dp[i] = true;
break;
}
}
}
return dp[s.length()];
}
public int firstUniqChar2(String s) {
if (s == null || s.length() == 0) {
return -1;
}
char[] sChar = s.toCharArray();
int[] bucket = new int [256];
for (int i = 0; i < sChar.length; i++) {
bucket[sChar[i]]++;
}
for (int i = 0; i < sChar.length; i++) {
if (bucket[sChar[i]] == 1) {
return i;
}
}
return -1;
}
public int firstUniqChar1(String s) {
if (s == null || s.length() == 0) {
return -1;
}
char[] sChar = s.toCharArray();
int[] bucket = new int [256];
Map<Character, Integer> map = new LinkedHashMap<>();
for (int i = 0; i < sChar.length; i++) {
if (bucket[sChar[i]]++ == 0) {
map.put(sChar[i], i);
} else {
map.remove(sChar[i]);
}
}
Iterator it = map.entrySet().iterator();
if (it.hasNext()) {
Map.Entry pair = (Map.Entry)it.next();
return (Integer)pair.getValue();
}
return -1;
}
private static TreeNode getLCA(TreeNode root, TreeNode n1, TreeNode n2) {
if (root == null) {
return null;
}
if (root == n1 || root == n2) {
return root;
}
TreeNode left = getLCA(root.left, n1, n2);
TreeNode right = getLCA(root.right, n1, n2);
if (left != null && right != null) {
return root;
}
if (left == null && right == null) {
return null;
}
return left == null? right: left;
}
private TreeNode prev1 = null;
private boolean validateBST1(TreeNode root) {
if (root == null) {
return true;
}
if (!validateBST1(root.left)) {
return false;
}
if (prev1 != null && prev1.val >= root.val) {
return false;
}
prev1 = root;
return validateBST1(root.right);
}
private boolean validateBST2(TreeNode root) {
if (root == null) {
return true;
}
Stack<TreeNode> stack = new Stack<>();
TreeNode prev = null;
while (root != null || !stack.isEmpty()) {
while (root != null) {
stack.push(root);
root = root.left;
}
root = stack.pop();
if (prev != null && prev.val >= root.val) {
return false;
}
prev = root;
root = root.right;
}
return true;
}
private boolean validateBST3(TreeNode root) {
return dvcq(root, Long.MIN_VALUE, Long.MAX_VALUE);
}
private boolean dvcq(TreeNode root, long min, long max) {
if (root == null) {
return true;
}
if (root.val <= min || root.val >= max) {
return false;
}
return dvcq(root.left, min, Math.min(root.val, max))
&& dvcq(root.right, Math.max(root.val, min), max);
}
private static String findPathBetween(TreeNode root, TreeNode start, TreeNode end) {
if (root == null) {
return "";
}
TreeNode lca = getLCA(root, start, end);
List<TreeNode> pathToStart = new ArrayList<TreeNode>();
findPathTo(lca, start, pathToStart);
List<TreeNode> pathToEnd = new ArrayList<TreeNode>();
findPathTo(lca, end, pathToEnd);
StringBuilder sb = new StringBuilder();
for (int i = pathToStart.size() - 1; i > 0; i--) {
if (sb.length() == 0) {
sb.append(pathToStart.get(i).val);
} else {
sb.append("->");
sb.append(pathToStart.get(i).val);
}
}
for (TreeNode node : pathToEnd) {
sb.append("->");
sb.append(node.val);
}
return sb.toString();
}
private static boolean findPathTo(TreeNode start, TreeNode end, List<TreeNode> curr) {
curr.add(start);
if (start == end) {
return true;
} else {
if (start.left != null) {
if (findPathTo(start.left, end, curr)) {
return true;
}
}
if (start.right != null) {
if (findPathTo(start.right, end, curr)) {
return true;
}
}
}
curr.remove(curr.size() - 1);
return false;
}
}
|