Merge pull request chipbk10#100 from chipbk10/Stack

Stack

Author: chipbk10

README.md

@@ -1,7 +1,7 @@
 # Topics:
 
 ### Handle Duplicate: 115, 730
-### Monotonic: 1135
+### Monotonic: 1135, 1130, 907, 901, 856, 503, 496, 84, 42, 739
 ### Intervals: 546, 312, 1000, 1353, 1288
 ### Game:
 ### Knapsack: 416, 518, 1049

src/contest/ReadMe.java

@@ -12,7 +12,7 @@ public class ReadMe {
     // dp:                  1349[!]     1340[v]     1367[v]     1388[!]
     // divide & conquer:    932[!]      514         903[v]      327[x]
     // greedy:              1354[!]     1353[x]     1338[v]     1383[!]
-    // stack:               1190[!]     975[x]      1381[v]     901
+    // stack:               1190[!]     975[x]      1381[v]     901[v]
     // binary search:       1351[v]     1337[v]     1292[!]     1235
     // 2 pointers:          1248[*]     1234[v]     986[v]      826
     // sliding window:      1208[v]     1040[!]     995[!]      567

src/stack/Problem901_OnlineStockSpan.java

@@ -0,0 +1,23 @@
+package stack;
+
+import java.util.Stack;
+
+public class Problem901_OnlineStockSpan {
+
+    class StockSpanner {
+
+        Stack<int[]> stack = new Stack<>();
+
+        public StockSpanner() {
+        }
+
+        public int next(int price) {
+            int res = 1;
+            while (!stack.isEmpty() && (stack.peek()[0] <= price)) {
+                res += stack.pop()[1];
+            }
+            stack.push(new int[] {price, res});
+            return res;
+        }
+    }
+}