Create number-of-ways-to-earn-points.cpp

Author: kamyu104

C++/number-of-ways-to-earn-points.cpp

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+// Time:  O(n * t * c)
+// Space: O(t)
+
+// knapsack dp
+class Solution {
+public:
+    int waysToReachTarget(int target, vector<vector<int>>& types) {
+        static const int MOD = 1e9 + 7;
+
+        vector<int> dp(target + 1);
+        dp[0] = 1;
+        for (const auto& t : types) {
+            for (int i = target; i >= 1; --i) {
+                for (int j = 1; j <= min(i / t[1], t[0]); ++j) {
+                    dp[i] = (dp[i] + dp[i - j * t[1]]) % MOD;
+                }
+            }
+        }
+        return dp.back();
+    }
+};
+
+// Time:  O(n * t * c)
+// Space: O(t)
+// knapsack dp
+class Solution2 {
+public:
+    int waysToReachTarget(int target, vector<vector<int>>& types) {
+        static const int MOD = 1e9 + 7;
+
+        vector<int> dp(target + 1);
+        dp[0] = 1;
+        for (const auto& t : types) {
+            vector<int> new_dp(target + 1);
+            for (int i = 0; i <= target; ++i) {
+                for (int j = 0; j <= min((target - i) / t[1], t[0]); ++j) {
+                    new_dp[i + j * t[1]] = (new_dp[i + j * t[1]] + dp[i]) % MOD;
+                }
+            }
+            dp = move(new_dp);
+        }
+        return dp.back();
+    }
+};