leetcode

Author: shangchun

reverseInteger.py

@@ -0,0 +1,23 @@
+# @return an integer
+def reverse(x):
+    maxint = 2**31 - 1
+    if x > 0:
+        sign = 1
+    else:
+        sign = -1
+        x = -x
+    r = 0
+    while x:
+        r = r * 10 + x % 10
+        if r > maxint:
+            return 0
+        x = x / 10
+    return r * sign
+
+assert reverse(123) == 321
+assert reverse(-123) == -321
+assert reverse(0) == 0
+assert reverse(-1) == -1
+assert reverse(1) == 1
+assert reverse(100) == 1
+assert reverse(10000000003) == 0

twoSum.py

@@ -0,0 +1,46 @@
+# @return a tuple, (index1, index2)
+def twoSum(num, target):
+    m = {}
+    for k in range(len(num)):
+        v = num[k]
+        remain = target - v
+        if remain in m:
+            return (m[remain], k + 1)
+        elif v not in m:
+            m[v] = k + 1
+    return -1
+
+    ## UGLY CODE!
+    # m = {}
+    # length = len(num)
+    # for i in range(length):
+    #     if num[i] not in m:
+    #         m[num[i]] = []
+    #     m[num[i]].append(i + 1);
+    # keys = m.keys()
+    # keys.sort()
+    # i = 0
+    # j = len(keys) - 1
+    # print m
+    # print keys
+    # while i <= j:
+    #     print i
+    #     print j
+    #     s = keys[i] + keys[j];
+    #     if s > target:
+    #         j = j - 1
+    #     elif s < target:
+    #         i = i + 1
+    #     else:
+    #         if i == j and len(m[keys[i]]) == 1:
+    #             return -1
+    #         elif m[keys[i]][0] < m[keys[j]][-1]:
+    #             return (m[keys[i]][0], m[keys[j]][-1])
+    #         else:
+    #             return (m[keys[j]][-1], m[keys[i]][0])
+    # return -1
+
+assert twoSum([2, 7, 11, 15], 9) == (1, 2)
+assert twoSum([2, 5, 21, 12], 26) == (2, 3)
+assert twoSum([150, 24, 79, 50, 88, 345, 3], 200) == (1, 4)
+assert twoSum([2, 1, 9, 4, 4, 56, 90, 3], 8) == (4, 5)