Create 26 December Akku and Binary Numbers

26 December Akku and Binary Numbers

@@ -0,0 +1,61 @@
+class Solution{
+private:
+    long long cnts[3][64];
+public:
+    void precompute()
+    {
+        // build searching table
+        cnts[0][63] = cnts[1][63] = cnts[2][63] = 0ll;
+
+        // Code Here
+        for (int i = 0; i < 63; i++) {
+            cnts[0][i] = i + 1;
+
+            if (i < 2) {
+                cnts[1][i] = 0;
+            } else {
+                cnts[1][i] = i - 1 + cnts[1][i-1];
+            }
+
+            if (i < 3) {
+                cnts[2][i] = 0;
+            } else {
+                cnts[2][i] = cnts[1][i-1] + cnts[2][i-1];
+            }
+        }
+    }
+
+    long long solve(long long l, long long r){
+        // Code Here
+        long long res = 0;
+
+        if (l < 1 || r < l || r > 1000000000000000000) {
+            return -1;
+        }
+
+        long long l_cnt = 0, r_cnt = 0;
+
+        // [l, r] ~ (l-1, r]
+        l--;
+
+        // searching all possible 3bits numbers from table
+        for (int i = 2; i >= 0; i--) {
+            if (l > 0) {
+                int cl = 63 - __builtin_clzll(l);
+                l_cnt += cnts[i][cl];
+
+                l ^= 1ll << cl;
+            }
+
+            if (r > 0) {
+                int cr = 63 - __builtin_clzll(r);
+                r_cnt += cnts[i][cr];
+
+                r ^= 1ll << cr;
+            }
+        }
+
+        return (r_cnt - l_cnt);
+    }
+
+};