Create 13 May | 2466. Count Ways To Build Good Strings.cpp

13 May | 2466. Count Ways To Build Good Strings.cpp

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+class Solution {
+    int mod = 1e9+7;
+    int solve(int target, int one, int zero, vector<int> &dp){
+        if(target == 0)
+            return 1;
+
+        if(target < 0)
+            return 0;
+
+        if(dp[target] != -1) return dp[target];
+        long long sum;
+        sum = solve(target-one, one, zero, dp) + solve(target-zero, one, zero, dp);
+        return dp[target] = sum%mod;
+    }
+public:
+    int countGoodStrings(int low, int high, int zero, int one) {
+        int ans = 0;
+        vector<int> dp(high+1, -1);
+
+        for(int i = low; i <= high; i++){
+            ans = ((ans%mod) + solve(i, one, zero, dp))%mod;
+        }
+        return ans;
+    }
+};