Create Solution.cpp

优化过的partition

Author: zouwx2cs

solution/0215.Kth Largest Element in an Array/Solution.cpp

@@ -0,0 +1,44 @@
+class Solution {
+public:
+    int findKthLargest(vector<int>& nums, int k) {
+        --k ;
+        int ii = 0, jj = nums.size()-1 ;
+        int i, j ;
+        while (true)
+        {
+            i = ii, j = jj ;
+            if (i + 63 < j)
+            {
+                const int mid = i + (j-i)/2 ;
+                if (nums[j] >= nums[mid] && nums[j] <= nums[i]
+                   || nums[j] <= nums[mid] && nums[j] >= nums[i])
+                {
+                    swap(nums[i], nums[j]) ;
+                }
+                else if (nums[mid] >= nums[i] && nums[mid] <= nums[j]
+                   || nums[mid] <= nums[i] && nums[mid] >= nums[j])
+                {
+                    swap(nums[i], nums[mid]) ;
+                }
+            }
+            while (i < j)
+            {
+                while (i < j && nums.at(i) >= nums.at(j))
+                    --j ;
+                swap(nums[i], nums[j]) ;
+                while (i < j && nums.at(i) >= nums.at(j))
+                    ++i ;
+                swap(nums[i], nums[j]) ;
+            }
+            
+            if (i > k)
+                jj = i-1 ;
+            else if (i < k)
+                ii = i+1 ;
+            else
+                return nums[k] ;
+        }
+        
+        return nums.at(k) ;
+    }
+};