Create 1155-number-of-dice-rolls-with-target-sum.js

Author: everthis

1155-number-of-dice-rolls-with-target-sum.js

@@ -0,0 +1,26 @@
+/**
+ * @param {number} d
+ * @param {number} f
+ * @param {number} target
+ * @return {number}
+ */
+const numRollsToTarget = function(d, f, target) {
+  const mod = 10 ** 9 + 7
+  if (target > d * f || target < d) {
+    return 0
+  }
+  const dp = new Array(target + 1).fill(0)
+  for (let i = 1; i < Math.min(f + 1, target + 1); i++) {
+    dp[i] = 1
+  }
+  for (let i = 2; i < d + 1; i++) {
+    for (let j = Math.min(target, i * f); j > i - 1; j--) {
+      dp[j] = 0
+      for (let k = Math.max(i - 1, j - f); k < j; k++) {
+        dp[j] = (dp[j] + dp[k]) % mod
+      }
+    }
+  }
+
+  return dp[target]
+}