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Author: wuduhren

problems/kth-largest-element-in-an-array.py

@@ -40,5 +40,27 @@ def findKthLargest(self, nums, k):
 """
 class Solution(object):
     def findKthLargest(self, nums, k):
-        #to be continued...
-        pass
+        def sortRange(A, l, r):
+            if l>=r: return A
+
+            p = A[(l+r)/2]
+            i = partition(A, l, r, p)
+            if k<i:
+                sortRange(A, l, i-1)
+            else:
+                sortRange(A, i, r)
+            return A
+
+        def partition(A, l, r, p):
+            while l<=r:
+                while A[l]<p: l += 1
+                while A[r]>p: r -= 1
+                if l<=r:
+                    A[l], A[r] = A[r], A[l]
+                    l += 1
+                    r -= 1
+            return l
+        
+        k = len(nums)-k #redefine the problem to find the kth nums when sorted
+        sortRange(nums, 0, len(nums)-1)
+        return nums[k]

problems/sort-colors.py

@@ -0,0 +1,45 @@
+class Solution(object):
+    def sortColors(self, nums):
+        l = 0
+        r = len(nums)-1
+        
+        i = 0
+        while i<=r:
+            if nums[i]==0:
+                nums[l], nums[i] = nums[i], nums[l]
+                l += 1
+                i += 1
+            elif nums[i]==2:
+                nums[i], nums[r] = nums[r], nums[i]
+                r -= 1
+            elif nums[i]==1:
+                i += 1
+
+# counting sort
+class Solution(object):
+    def sortColors(self, nums):
+        count0 = count1 = count2 = 0
+        
+        for num in nums:
+            if num==0:
+                count0 += 1
+            elif num==1:
+                count1 += 1
+            elif num==2:
+                count2 += 1
+        
+        i = 0
+        while count0>0:
+            nums[i] = 0
+            i += 1
+            count0 -= 1
+            
+        while count1>0:
+            nums[i] = 1
+            i += 1
+            count1 -= 1
+            
+        while count2>0:
+            nums[i] = 2
+            i += 1
+            count2 -= 1