add 901

Author: fishercoder1534

README.md

@@ -236,6 +236,7 @@ _If you like this project, please leave me a star._ ★
 |914|[X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_914.java) |  |Easy|
 |912|[Sort an Array](https://leetcode.com/problems/sort-an-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_912.java) |  |Easy|
 |908|[Smallest Range I](https://leetcode.com/problems/smallest-range-i/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_908.java) |  |Easy|
+|901|[Online Stock Span](https://leetcode.com/problems/online-stock-span/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_901.java) |  |Medium| Stack
 |900|[RLE Iterator](https://leetcode.com/problems/rle-iterator/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_900.java) |  |Medium|
 |897|[Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_897.java) | |Easy| DFS, recursion
 |896|[Monotonic Array](https://leetcode.com/problems/monotonic-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_896.java) |  |Easy|

src/main/java/com/fishercoder/solutions/_901.java

@@ -0,0 +1,24 @@
+package com.fishercoder.solutions;
+
+import java.util.Stack;
+
+public class _901 {
+    public static class Solution1 {
+        public static class StockSpanner {
+            Stack<int[]> stack;
+
+            public StockSpanner() {
+                stack = new Stack<>();
+            }
+
+            public int next(int price) {
+                int result = 1;
+                while (!stack.isEmpty() && stack.peek()[0] <= price) {
+                    result += stack.pop()[1];
+                }
+                stack.push(new int[]{price, result});
+                return result;
+            }
+        }
+    }
+}

src/test/java/com/fishercoder/_901Test.java

@@ -0,0 +1,23 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._901;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _901Test {
+    private static _901.Solution1.StockSpanner stockSpanner;
+
+    @Test
+    public void test1() {
+        stockSpanner = new _901.Solution1.StockSpanner();
+        assertEquals(1, stockSpanner.next(100));
+        assertEquals(1, stockSpanner.next(80));
+        assertEquals(1, stockSpanner.next(60));
+        assertEquals(2, stockSpanner.next(70));
+        assertEquals(1, stockSpanner.next(60));
+        assertEquals(4, stockSpanner.next(75));
+        assertEquals(6, stockSpanner.next(85));
+    }
+
+}