sync

src/s101/Test160.scala

@@ -0,0 +1,51 @@
+package s101
+
+import util.ListNode
+
+object Test160 {
+  def getIntersectionNode(headA: ListNode, headB: ListNode): ListNode = {
+    // 如果第一个节点即为相交节点，则直接返回
+    if (headA == headB) return headA
+
+    var pa = headA
+    var pb = headB
+
+    var aLen = 0
+    var bLen = 0
+
+    // 想让pa,pb遍历到底,计算长度。
+    while (pa.next != null) {
+      pa = pa.next
+      aLen += 1
+    }
+
+    while (pb.next != null) {
+      pb = pb.next
+      bLen += 1
+    }
+
+    // 得到两个链表的长度差距
+    val diff = aLen - bLen
+    pa = headA
+    pb = headB
+    if (diff < 0) {
+      // 链表b更长, 是b向后移-diff次
+      for (elem <- 0.until(diff, -1)) {
+        pb = pb.next
+      }
+    } else if (diff > 0) {
+      // 链表a更长
+      for (elem <- 0.until(diff)) {
+        pa = pa.next
+      }
+    } else {
+      // 一样长，不做处理
+    }
+
+    while (pa != pb && pa != null && pb != null) {
+      pa = pa.next
+      pb = pb.next
+    }
+    pa
+  }
+}

src/s801/Test876.scala

@@ -0,0 +1,25 @@
+package s801
+
+import util.ListNode
+
+object Test876 {
+  def middleNode(head: ListNode): ListNode = {
+    // 快指针一次走两步，慢指针一次走一步
+    var slow = head
+    var fast = head
+    while (fast.next != null && fast.next.next != null) {
+      // fast的后两位都不是null，则其可以向后移动
+      slow = slow.next
+      fast = fast.next.next
+    }
+
+    if (fast.next == null){
+      // 如果后一位为null，说明是奇数
+      slow
+    }else{
+      // 否则是偶数
+      slow.next
+    }
+
+  }
+}