digit dp

Author: tmp-coder

kick-start/no-line-kickstart-roundB.cpp

@@ -0,0 +1,41 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+typedef long long LL;
+
+LL dp[20][10][2];
+
+
+LL calc(int pos,int sum,bool less, const string & num){
+    if(pos ==num.size())
+        return sum !=0;
+    if(dp[pos][sum][less] != -1)
+        return dp[pos][sum][less];
+    
+    int lmt = less ? num[pos] -'0':8;
+    if(lmt ==9)lmt =8;
+    LL ret =0;
+    for(int i=0 ; i<=lmt ; ++i){
+        ret += calc(pos +1,(sum +i) % 9, less && i==lmt ,num);
+    }
+    return dp[pos][sum][less] = ret;
+}
+
+LL solve(LL n){
+    memset(dp,-1,sizeof(dp));
+    string s = to_string(n);
+    return calc(0,0,1,s);
+}
+
+int main(){
+    int T;
+    cin >> T;
+    for(int t=1 ; t <= T; ++t){
+        LL n,m;
+        cin >> n >> m;
+        // cout << "solve(n-1) = " <<solve(n-1) << "\n";
+        // cout << "solve(m) = " <<solve(m) << "\n";
+        LL ans = solve(m) - solve(n-1);
+        cout << "Case #"<<t <<": "<< ans << '\n';
+    }
+}