3

Author: kedebug

SortColors/SortColors.cpp

@@ -0,0 +1,49 @@
+
+class Solution {
+public:
+    void sortColors(int A[], int n) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        
+        int low = 0, high = n - 1;
+        int mid = 0;
+        
+        while (mid <= high) {
+            if (A[mid] == 0) {
+                A[mid++] = A[low];
+                A[low++] = 0;
+            }
+            else if (A[mid] == 1) {
+                mid += 1;
+            }
+            else if (A[mid] == 2) {
+                A[mid] = A[high];
+                A[high--] = 2;
+            }
+        }
+    }
+};
+
+//
+// Solution2 using the method like quicksort
+//
+class Solution2 {
+public:
+    void sortColors(int A[], int n) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        
+        int p = split(A, 0, n - 1, 0);
+        split(A, p + 1, n - 1, 1);
+    }
+    int split(int A[], int low, int high, int pivot) {
+        int i = low - 1;
+        for (int j = low; j <= high; j++) {
+            if (A[j] <= pivot) {
+                i += 1;
+                if (i != j) swap(A[i], A[j]);
+            }
+        }
+        return i;
+    }
+};