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-rw-r--r--new_21_game.c19
-rw-r--r--new_21_game.py39
2 files changed, 48 insertions, 10 deletions
diff --git a/new_21_game.c b/new_21_game.c
index 4076f33..a9a0f5a 100644
--- a/new_21_game.c
+++ b/new_21_game.c
@@ -1,37 +1,36 @@
// 837. New 21 Game
-#include <stdio.h>
-#include <stdlib.h>
+#include "leetcode.h"
/*
* alice plays the following game, loosely based on the card game "21". alice
* starts with 0 points and draws numbers while she has less than 'k' points.
* during each draw, she gains an integer number of points randomly from range
- * '[1, max_pts]', where 'max_pts' is an integer. each draw is independent and
+ * '[1, maxPts]', where 'maxPts' is an integer. each draw is independent and
* the outcomes have equal posibilities. alice stops drawing numbers when she
* gets 'k' or more points. return the probability that alice has 'n' or fewer
* points. answers within 10^-5 of the actual answer are considered accepted
*/
-double new21Game(int n, int k, int max_pts) {
- if (!k || n >= k + max_pts)
+double new21Game(int n, int k, int maxPts) {
+ if (!k || n >= k + maxPts)
return 1.0;
- double *dp = malloc((n + 1) * sizeof(double));
+ double *dp = (double *)malloc((n + 1) * sizeof(double));
dp[0] = 1.0;
double sum = 1.0, ans = 0.0;
for (int i = 1; i <= n; ++i) {
- dp[i] = sum / max_pts;
+ dp[i] = sum / maxPts;
if (i < k)
sum += dp[i];
else
ans += dp[i];
- if (i - max_pts >= 0)
- sum -= dp[i - max_pts];
+ if (i - maxPts >= 0)
+ sum -= dp[i - maxPts];
}
+ free(dp);
return ans;
}
int main() {
- // new21Game(21,17,10);
printf("%f\n", new21Game(10, 1, 10)); // expect: 1.00000
printf("%f\n", new21Game(6, 1, 10)); // expect: 0.60000
printf("%f\n", new21Game(21, 17, 10)); // expect: 0.73278
diff --git a/new_21_game.py b/new_21_game.py
new file mode 100644
index 0000000..cc634d0
--- /dev/null
+++ b/new_21_game.py
@@ -0,0 +1,39 @@
+# 837. New 21 Game
+
+"""
+alice plays the following game, loosely based on the card game "21". alice
+starts with 0 points and draws numbers while she has less than 'k' points.
+during each draw, she gains an integer number of points randomly from range
+'[1, maxPts]', where 'maxPts' is an integer. each draw is independent and
+the outcomes have equal posibilities. alice stops drawing numbers when she
+gets 'k' or more points. return the probability that alice has 'n' or fewer
+points. answers within 10^-5 of the actual answer are considered accepted
+"""
+
+
+class Solution(object):
+ def new21Game(self, n, k, maxPts):
+ """
+ :type n: int
+ :type k: int
+ :type maxPts: int
+ :rtype: float
+ """
+ if k == 0 or n >= k + maxPts:
+ return 1
+ dp = [1.0] + [0.0] * n
+ sum = 1.0
+ for i in range(1, n + 1):
+ dp[i] = sum / maxPts
+ if i < k:
+ sum += dp[i]
+ if i - maxPts >= 0:
+ sum -= dp[i - maxPts]
+ return sum(dp[k:])
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ print(obj.new21Game(n=10, k=1, maxPts=10))
+ print(obj.new21Game(n=6, k=1, maxPts=10))
+ print(obj.new21Game(n=21, k=17, maxPts=10))