Create number-of-dice-rolls-with-target-sum.cpp

Author: kamyu104

C++/number-of-dice-rolls-with-target-sum.cpp

@@ -0,0 +1,20 @@
+// Time:  O(d * f * t)
+// Space: O(t)
+
+class Solution {
+public:
+    int numRollsToTarget(int d, int f, int target) {
+        static const int MOD = 1e9 + 7;
+        vector<vector<int>> dp(2, vector<int>(target + 1));
+        dp[0][0] = 1;
+        for (int i = 1; i <= d; ++i) {
+            dp[i % 2] = vector<int>(target + 1);
+            for (int k = 1; k <= f; ++k) {
+                for (int j = k; j <= target; ++j) {
+                    dp[i % 2][j] = (dp[i % 2][j] + dp[(i - 1) % 2][j - k]) % MOD;
+                }
+            }
+        }
+        return dp[d % 2][target] % MOD;
+    }
+};