Update solution

solution/013.Roman to Integer/Solution.py

@@ -0,0 +1,21 @@
+class Solution:
+    def romanToInt(self, s):
+        """
+        :type s: str
+        :rtype: int
+        """
+        r2i={'M':1000,'CM':900,'D':500,'CD':400,'C':100,'XC':90,'L':50,'CL':40,'X':10,'IX':9,'V':5,'IV':4,'I':1}
+        i=0
+        result=0
+        while 1:
+            if i<=(len(s)-1):
+                try:
+                    if r2i[s[i:(i+2)]]:
+                        result += r2i[s[i:(i+2)]]
+                        i=i+2
+                except:
+                    result += r2i[s[i]]
+                    i=i+1
+            else:
+                break
+        return result

solution/024.Swap Nodes in Pairs/Solution.py

@@ -0,0 +1,28 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution:
+    def swapPairs(self, head):
+        """
+        :type head: ListNode
+        :rtype: ListNode
+        """
+        if (not head) or (not head.next):
+            return head
+        pre=head.next
+        p=head
+        q=head.next
+
+        while q:
+            t=q.next
+            q.next=p
+            if (not t) or (not t.next):
+                p.next=t
+                break
+            p.next=t.next
+            p=t
+            q=p.next
+        return pre

solution/203.Remove Linked List Elements/Solution.py

@@ -0,0 +1,20 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution:
+    def removeElements(self, head, val):
+        """
+        :type head: ListNode
+        :type val: int
+        :rtype: ListNode
+        """
+        if head == None:
+            return None
+        head.next=self.removeElements(head.next,val)
+        if head.val == val:
+            return head.next
+        else:
+            return head