From dffe9459dd30e27fddfdb8a2da0b3a95fe8fe2ea Mon Sep 17 00:00:00 2001
From: Hrishikesh S <hrishikesh123s@gmail.com>
Date: Sun, 6 Oct 2019 13:09:42 +0530
Subject: [PATCH] added solution & modified README.md for problem 121

---
 leetcode/README.md |  3 ++-
 leetcode/src/121.c | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 leetcode/src/121.c

diff --git a/leetcode/README.md b/leetcode/README.md
index 9c8402df..0c370e42 100644
--- a/leetcode/README.md
+++ b/leetcode/README.md
@@ -23,6 +23,7 @@ LeetCode
 |109|[Convert Sorted List to Binary Search Tree](https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/) | [C](./src/109.c)|Medium|
 |110|[Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/) | [C](./src/110.c)|Easy|
 |112|[Path Sum](https://leetcode.com/problems/path-sum/) | [C](./src/112.c)|Easy|
+|121|[Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/) | [C](./src/121.c)|Easy|
 |125|[Valid Palindrome](https://leetcode.com/problems/valid-palindrome/) | [C](./src/125.c)|Easy|
 |136|[Single Number](https://leetcode.com/problems/single-number/) | [C](./src/136.c)|Easy|
 |141|[Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/) | [C](./src/141.c)|Easy|
@@ -67,4 +68,4 @@ LeetCode
 |938|[Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/) | [C](./src/938.c)|Easy|
 |965|[Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree/) | [C](./src/965.c)|Easy|
 |977|[Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array/) | [C](./src/977.c)|Easy|
-|1189|[Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons/) | [C](./src/1189.c)|Easy|
\ No newline at end of file
+|1189|[Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons/) | [C](./src/1189.c)|Easy|
diff --git a/leetcode/src/121.c b/leetcode/src/121.c
new file mode 100644
index 00000000..45433806
--- /dev/null
+++ b/leetcode/src/121.c
@@ -0,0 +1,27 @@
+int maxProfit(int* prices, int pricesSize){
+	/* If there is only only one day, profit cannot be made
+	 */
+	if(pricesSize <= 1) {
+        return 0;
+    }
+    int min_element = prices[0];
+    int max_difference = prices[1] - min_element;
+    for(int i = 0; i < pricesSize; i++) {
+		/* whenever maximum profit can be made, we sell the stock.
+           so we change the maximum difference
+		 */
+        if(prices[i] - min_element > max_difference) {
+            max_difference = prices[i] - min_element;
+		}
+		/* if a cheaper stock is available, we make that the minimum element
+		 */
+        if(min_element > prices[i]) {
+            min_element = prices[i];
+		}
+    }
+	/* return 0 if max_difference is less than zero, incase there is no way of making profits
+	 */
+    return (max_difference < 0)? 0 : max_difference;
+}
+
+