modify code on class

Author: algorithmzuo

src/topinterviewquestions/Problem_0130_SurroundedRegions.java

@@ -83,7 +83,6 @@ public static void solve2(char[][] board) {
 				if (board[i][j] == 'F') {
 					board[i][j] = 'O';
 				}
-
 			}
 		}
 	}

src/topinterviewquestions/Problem_0138_CopyListWithRandomPointer.java

@@ -20,6 +20,8 @@ public static Node copyRandomList(Node head) {
 		}
 		Node cur = head;
 		Node next = null;
+		// 1 -> 2 -> 3 -> null
+		// 1 -> 1' -> 2 -> 2' -> 3 -> 3'
 		while (cur != null) {
 			next = cur.next;
 			cur.next = new Node(cur.val);
@@ -28,6 +30,8 @@ public static Node copyRandomList(Node head) {
 		}
 		cur = head;
 		Node copy = null;
+		// 1 1' 2 2' 3 3'
+		// 依次设置 1' 2' 3' random指针
 		while (cur != null) {
 			next = cur.next.next;
 			copy = cur.next;
@@ -36,6 +40,8 @@ public static Node copyRandomList(Node head) {
 		}
 		Node res = head.next;
 		cur = head;
+		// 老 新 混在一起，next方向上，random正确
+		// next方向上，把新老链表分离
 		while (cur != null) {
 			next = cur.next.next;
 			copy = cur.next;

src/topinterviewquestions/Problem_0139_WordBreak.java

@@ -1,19 +1,10 @@
 package topinterviewquestions;
 
+import java.util.HashSet;
 import java.util.List;
 
 public class Problem_0139_WordBreak {
 
-	public static class Node {
-		public boolean end;
-		public Node[] nexts;
-
-		public Node() {
-			end = false;
-			nexts = new Node[26];
-		}
-	}
-
 	public static boolean wordBreak(String s, List<String> wordDict) {
 		Node root = new Node();
 		for (String str : wordDict) {
@@ -50,4 +41,94 @@ public static boolean wordBreak(String s, List<String> wordDict) {
 		return dp[0];
 	}
 
+	public static boolean wordBreak2(String s, List<String> wordDict) {
+		return process(s, 0, new HashSet<>(wordDict)) != 0;
+	}
+
+	// s[0......index-1]这一段，已经分解过了，不用在操心
+	// s[index.....] 这一段字符串，能够被分解的方法数，返回
+	public static int process(String s, int index, HashSet<String> wordDict) {
+		if (index == s.length()) {
+			return 1;
+		}
+		// index没到最后
+		// index...index
+		// index...index+1
+		// index....index+2
+		// index....end
+		int ways = 0;
+		for (int end = index; end < s.length(); end++) {
+			// s[index....end]
+			String pre = s.substring(index, end + 1);
+			if (wordDict.contains(pre)) {
+				ways += process(s, end + 1, wordDict);
+			}
+		}
+		return ways;
+	}
+
+	public static boolean wordBreak3(String s, List<String> wordDict) {
+		HashSet<String> set = new HashSet<>(wordDict);
+		int N = s.length();
+		int[] dp = new int[N + 1];
+		// dp[i] = process(s, i, set)的返回值
+		dp[N] = 1;
+		for (int index = N - 1; index >= 0; index--) {
+			int ways = 0;
+			for (int end = index; end < s.length(); end++) {
+				// s[index....end]
+				String pre = s.substring(index, end + 1);
+				if (set.contains(pre)) {
+					ways += dp[end + 1];
+				}
+			}
+			dp[index] = ways;
+		}
+		return dp[0] != 0;
+	}
+
+	public static class Node {
+		public boolean end;
+		public Node[] nexts;
+
+		public Node() {
+			end = false;
+			nexts = new Node[26];
+		}
+	}
+
+	public static boolean wordBreak4(String s, List<String> wordDict) {
+		Node root = new Node();
+		for (String str : wordDict) {
+			char[] chs = str.toCharArray();
+			Node node = root;
+			int index = 0;
+			for (int i = 0; i < chs.length; i++) {
+				index = chs[i] - 'a';
+				if (node.nexts[index] == null) {
+					node.nexts[index] = new Node();
+				}
+				node = node.nexts[index];
+			}
+			node.end = true;
+		}
+		char[] str = s.toCharArray();
+		int N = str.length;
+		int[] dp = new int[N + 1];
+		dp[N] = 1;
+		for (int i = N - 1; i >= 0; i--) {
+			Node cur = root;
+			for (int end = i; end < N; end++) {
+				cur = cur.nexts[str[end] - 'a'];
+				if (cur == null) {
+					break;
+				}
+				if (cur.end) {
+					dp[i] += dp[end + 1];
+				}
+			}
+		}
+		return dp[0] != 0;
+	}
+
 }

src/topinterviewquestions/Problem_0146_LRUCache.java

@@ -60,34 +60,35 @@ public void addNode(Node<K, V> newNode) {
 		}
 
 		public void moveNodeToTail(Node<K, V> node) {
-			if (this.tail == node) {
+			if (tail == node) {
 				return;
 			}
-			if (this.head == node) {
-				this.head = node.next;
-				this.head.last = null;
+			// node 不是尾巴
+			if (head == node) {
+				head = node.next;
+				head.last = null;
 			} else {
 				node.last.next = node.next;
 				node.next.last = node.last;
 			}
-			node.last = this.tail;
+			node.last = tail;
 			node.next = null;
-			this.tail.next = node;
-			this.tail = node;
+			tail.next = node;
+			tail = node;
 		}
 
 		public Node<K, V> removeHead() {
-			if (this.head == null) {
+			if (head == null) {
 				return null;
 			}
-			Node<K, V> res = this.head;
-			if (this.head == this.tail) { // 链表中只有一个节点的时候
-				this.head = null;
-				this.tail = null;
+			Node<K, V> res = head;
+			if (head == tail) { // 链表中只有一个节点的时候
+				head = null;
+				tail = null;
 			} else {
-				this.head = res.next;
+				head = res.next;
 				res.next = null;
-				this.head.last = null;
+				head.last = null;
 			}
 			return res;
 		}
@@ -123,12 +124,12 @@ public void set(K key, V value) {
 				node.value = value;
 				nodeList.moveNodeToTail(node);
 			} else {
+				if (keyNodeMap.size() == capacity) {
+					removeMostUnusedCache();
+				}
 				Node<K, V> newNode = new Node<K, V>(key, value);
 				keyNodeMap.put(key, newNode);
 				nodeList.addNode(newNode);
-				if (keyNodeMap.size() == capacity + 1) {
-					removeMostUnusedCache();
-				}
 			}
 		}
 

src/topinterviewquestions/Problem_0149_MaxPointsOnALine.java

@@ -12,14 +12,22 @@ public static int maxPoints(int[][] points) {
 		if (points.length <= 2) {
 			return points.length;
 		}
+		// Map<String, Integer>   "3_5"   6
+		// 3 / 5    4
+		// 3 / 7    10
+		// 3 / 17   11
+		// 5 / 7    9
+		// 5 / 9    3
+		// 3 :    (  5 , 4    7, 10,      17 ,  11      )
+		// 5 :    (  7 , 9    9, 3  )
 		Map<Integer, Map<Integer, Integer>> map = new HashMap<Integer, Map<Integer, Integer>>();
 		int result = 0;
 		for (int i = 0; i < points.length; i++) {
 			map.clear();
 			int samePosition = 1;
 			int sameX = 0;
 			int sameY = 0;
-			int line = 0;
+			int line = 0; // 哪个斜率压中的点最多，把最多的点的数量，赋值给line
 			for (int j = i + 1; j < points.length; j++) {
 				int x = points[j][0] - points[i][0];
 				int y = points[j][1] - points[i][1];

src/topinterviewquestions/Problem_0152_MaximumProductSubarray.java

@@ -6,6 +6,7 @@ public static int maxProduct(int[] nums) {
 		int ans = nums[0];
 		int min = nums[0];
 		int max = nums[0];
+		// [0]   
 		for (int i = 1; i < nums.length; i++) {
 			int curmin = Math.min(nums[i], Math.min(min * nums[i], max * nums[i]));
 			int curmax = Math.max(nums[i], Math.max(min * nums[i], max * nums[i]));

src/topinterviewquestions/Problem_0160_IntersectionOfTwoLinkedLists.java

@@ -18,14 +18,16 @@ public static ListNode getIntersectionNode(ListNode head1, ListNode head2) {
 			n++;
 			cur1 = cur1.next;
 		}
+		// cur1  end1
 		while (cur2.next != null) {
 			n--;
 			cur2 = cur2.next;
 		}
+		// cur2 end2
 		if (cur1 != cur2) {
 			return null;
 		}
-		cur1 = n > 0 ? head1 : head2;
+		cur1 = n > 0 ? head1 : head2; // 谁是长链表，谁把头节点，给cur1赋值
 		cur2 = cur1 == head1 ? head2 : head1;
 		n = Math.abs(n);
 		while (n != 0) {

src/topinterviewquestions/Problem_0190_ReverseBits.java

@@ -38,6 +38,7 @@ public class Problem_0190_ReverseBits {
 
 
 	public static int reverseBits(int n) {
+		// n
 		n = (n >>> 16) | (n << 16);
 		n = ((n & 0xff00ff00) >>> 8) | ((n & 0x00ff00ff) << 8);
 		n = ((n & 0xf0f0f0f0) >>> 4) | ((n & 0x0f0f0f0f) << 4);