Create code.cpp

LCCUP/2020Fall/LCP25.古董键盘/code.cpp

@@ -0,0 +1,34 @@
+class Solution {
+    long dp[131][27];
+public:
+    int keyboard(int k, int n) 
+    {
+        long comb[131][131];  
+        long M = 1e9+7;
+
+        for (int j=0; j<=26; j++)
+            dp[0][j] = 1;
+
+        for (int i = 0; i <= n; ++i) 
+        {
+            comb[i][i] = comb[i][0] = 1;    
+            if (i==0) continue;        
+            for (int j = 1; j <= min(n, k); ++j) 
+            {
+                comb[i][j] = comb[i - 1][j - 1] + comb[i - 1][j];
+                comb[i][j] %= M;
+            }
+        }
+
+        for (int i=1; i<=n; i++)
+            for (int j=1; j<=26; j++)
+            {                
+                for (int t = 0; t <= min(i, k); t++)
+                {
+                    dp[i][j] += dp[i-t][j-1] * comb[i][t];
+                    dp[i][j] %= M;
+                }                    
+            }
+        return dp[n][26];
+    }
+};