leetcode 85

leetcode/75_sort_colors.cpp

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+#include<bits/stdc++.h>
+using namespace std;
+
+// Solution 1 - Sort Using merge sort - Time O(nlogn)
+// Solution 2 - Using counting sort - Time O(2N) - i.e. requires 2 passes
+
+// --------------------------------------------- Optimal Solution - Dutch National Flag Algo | Time O(n) | Space - O(1)
+void sortColors(vector<int>& nums) {
+	int low = 0, mid = 0, high = nums.size() - 1;
+
+	while(mid <= high) {
+		switch (nums[mid])
+		{
+		case 0:
+			swap(nums[low++], nums[mid++]);
+			break;
+		case 1:
+			mid++;
+			break;
+		case 2:
+			swap(nums[mid], nums[high--]);
+			break;
+		}
+	}
+}
+
+int main() {
+	int n;
+	vector<int> nums;
+	cin>>n;
+
+
+	for(int i = 0; i < n; i++){
+		int x;
+		cin>>x;
+		nums.emplace_back(x);
+	}
+
+	sortColors(nums);
+
+	for(auto it: nums){
+		cout<<it<<" ";
+	}
+}