update solution

Author: selfboot

DivideConquer/215_KthLargestElementArray.cpp

@@ -1,6 +1,6 @@
 /*
  * @Author: [email protected]
- * @Last Modified time: 2016-08-29 11:18:00
+ * @Last Modified time: 2016-08-30 09:42:07
  */
 
 class Solution {
@@ -29,28 +29,30 @@ class Solution {
         return pivot_index;
     }
 
-    int findKthLargest(vector<int> &nums, int k) {
-        int left = 0, right = nums.size();
-        if(k>right || k<=0) return -1;
+    int find_kth_number(vector<int> &arr, int k){
+        int begin = 0, end = arr.size();
+        assert(k>0 && k<=end);
 
-        while(left < right){
-            int pos = partition(nums, left, right);
+        int target_num = 0;
+        while (begin < end){
+            int pos = partition(arr, begin, end);
             if(pos == k-1){
-                return nums[pos];
+                target_num = arr[pos];
+                break;
             }
             else if(pos > k-1){
-                right = pos;
+                end = pos;
             }
             else{
-                left = pos + 1;
+                begin = pos + 1;
             }
         }
-        return -1;
+        return target_num;
     }
 };
 
 
-class Solution {
+class Solution_2 {
 public:
     /*
     Other possibility is to use a min heap that will store the K-th largest values.

TwoPointers/75_SortColors.cpp

@@ -0,0 +1,31 @@
+/*
+ * @Author: [email protected]
+ * @Last Modified time: 2016-08-30 13:04:54
+ */
+
+class Solution {
+public:
+    // Wiki: https://en.wikipedia.org/wiki/Dutch_national_flag_problem
+    void sortColors(vector<int>& nums) {
+        int pos_put_red = 0, pos_put_blue = nums.size()-1;
+        int scan_index = 0;
+        while(scan_index <= pos_put_blue){
+            if(nums[scan_index] == 0){
+                swap(nums[scan_index++], nums[pos_put_red++]);
+            }
+            else if(nums[scan_index] == 2){
+                swap(nums[scan_index], nums[pos_put_blue--]);
+            }
+            else{
+                scan_index ++;
+            }
+        }
+    }
+};
+
+/*
+[0]
+[1,0]
+[0,1,2]
+[1,1,1,2,0,0,0,0,2,2,1,1,2]
+*/

TwoPointers/75_SortColors.py

@@ -4,10 +4,6 @@
 
 class Solution(object):
     def sortColors(self, nums):
-        """
-        :type nums: List[int]
-        :rtype: void Do not return anything, modify nums in-place instead.
-        """
         len_n = len(nums)
         # pos_put_0: next position to put 0
         # pos_put_2: next position to put 2
@@ -29,5 +25,7 @@ def sortColors(self, nums):
 
 """
 [0]
+[1,0]
+[0,1,2]
 [1,1,1,2,0,0,0,0,2,2,1,1,2]
 """