leetcode 1-3 26

Author: imbaliking

new_issue/ZConvert.py

@@ -0,0 +1,27 @@
+def convert(s, numRows):
+    """
+    :type s: str
+    :type numRows: int
+    :rtype: str
+    """
+    n = len(s)
+    if numRows == 1:
+        return s
+
+    row_num = min(n, numRows)
+    rows = [""] * row_num
+    going_down = False
+    current_row = 0
+    for i in range(n):
+        rows[current_row] += s[i]
+        if current_row == 0 or current_row == row_num - 1:
+            going_down = not going_down
+        current_row += 1 if going_down else -1
+
+    return "".join(rows)
+
+if __name__ == "__main__":
+    s= "PAYPALISHIRING"
+    numRows = 3
+    print convert(s,numRows)
+    

new_issue/findMedianSortedArrays.py

@@ -0,0 +1,17 @@
+
+def findMedianSortedArrays(num1,num2):
+    len1 = len(num1)
+    len2 = len(num2)
+    sum_len = len1+len2
+    all_len = sorted(num1 + num2)
+    if (sum_len)%2 == 0:
+        mid = ((sum_len)/2-1,(sum_len/2))
+        return (float(all_len[mid[0]]) + float(all_len[mid[1]]))/2
+    else:
+        mid = int(sum_len/2)
+        return float(all_len[mid])
+
+if __name__ == "__main__":
+    nums1 = [-1,0,2,3,109]
+    nums2 = [2,73,984]
+    print findMedianSortedArrays(nums1,nums2)

new_issue/longestPalindrome.py

@@ -0,0 +1,40 @@
+# coding:utf-8
+def longestPalindrome(s):
+    n = len(s)
+    if n < 2:
+        return s
+    max_length = 1
+    ret = s[0]
+
+    # 设定动态规划的状态标识数组
+    dp = [[False]*n for _ in range(n)]
+    # 字符串长度为0时一定为True
+    for i in range(n):
+        dp[i][i] = True
+    # 从2开始，因为i必须小于j
+    for a in range(2,n+1):
+        for i in range(n):
+            j = a + i - 1
+
+            if j >= n:
+                break
+            if s[i] != s[j]:
+                dp[i][j] = False
+            else:
+                # 处理字符串长度为1和2的情况
+                if j - i < 3:
+                    dp[i][j] = True
+                else:
+                    dp[i][j] = dp[i+1][j-1]
+
+            if dp[i][j] and j-i+1 > max_length:
+                ret = s[i:j+1]
+                max_length = j-i+1
+    return ret
+
+
+
+if __name__ == "__main__":
+    #s = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabcaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+    s = "ac"
+    print longestPalindrome(s)

new_issue/reverse.py

@@ -0,0 +1,27 @@
+def reverse(x):
+    """
+    :type x: int
+    :rtype: int
+    """
+    if x == 0:
+        return 0
+
+    isNav = x < 0
+    a = str(x)
+    b = a[1:][::-1] if isNav else a[::-1]
+    ret = int(b)
+    top_limit = 2 >> 30
+    if isNav:
+        if ret > top_limit:
+            return 0
+        else:
+            return -ret
+    if ret > top_limit - 1:
+        return 0
+    else:
+        return ret
+
+
+if __name__ == "__main__":
+    x = 13843135
+    print reverse(x)