add 837 new 21 game

Author: everthis

496-next-greater-element-I.js

@@ -21,4 +21,5 @@ const nextGreaterElement = function(findNums, nums) {
 };
 
 console.log(nextGreaterElement([4,1,2], [1,3,4,2]))
-console.log(nextGreaterElement([2,4], [1,2,3,4]))
+console.log(nextGreaterElement([2,4], [1,2,3,4]))
+console.log(nextGreaterElement([1,2,3], [9, 8, 7, 3, 2, 1, 6]))

837-new-21-game.js

@@ -0,0 +1,31 @@
+/**
+ * @param {number} N
+ * @param {number} K
+ * @param {number} W
+ * @return {number}
+ */
+const new21Game = function(N, K, W) {
+    if (K === 0 || N >= K + W) {
+        return 1
+    }
+    const dp = []
+    let Wsum = 1
+    let res = 0
+    dp[0] = 1
+    for (let i = 1; i <= N; i++) {
+        dp[i] = Wsum / W
+        if (i < K) {
+            Wsum += dp[i]
+        } else {
+            res += dp[i]
+        }
+        if (i - W >= 0) {
+            Wsum -= dp[i - W]
+        }
+    }
+    return res
+};
+
+console.log(new21Game(6,1,10))
+console.log(new21Game(10,1,10))
+console.log(new21Game(21,17,10))