Time: 17 ms (61.03%), Space: 20.3 MB (14.61%) - LeetHub

2466-count-ways-to-build-good-strings/2466-count-ways-to-build-good-strings.cpp

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+class Solution {
+    #define ll long long
+public:
+    ll mod=1e9+7;
+    ll c(ll len,ll low,ll high,vector<ll>&dp,int zero,int one){
+        if(len>high)return 0;
+        if(dp[len]!=-1)return dp[len];
+        ll ans=0;
+        if(len>=low && len<=high)ans=1;
+        ans += c(len+zero,low,high,dp,zero,one)%mod;
+        ans =  (ans%mod + c(len+one,low,high,dp,zero,one)%mod)%mod;
+        dp[len]=ans;
+        return ans;
+    }
+    int countGoodStrings(int low, int high, int zero, int one) {
+        vector<ll>dp(high+1,-1);
+        return c(0,low,high,dp,zero,one);   
+    }
+};