O(n) time and O(n) space

Author: 149ps

1680. Concatenation of Consecutive Binary Numbers/1680. 1680. Concatenation of Consecutive Binary Numbers.py

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+"""
+Given an integer n, return the decimal value of the binary string formed by concatenating the binary representations of 1 to n in order, modulo 109 + 7.
+
+
+
+Example 1:
+
+Input: n = 1
+Output: 1
+Explanation: "1" in binary corresponds to the decimal value 1.
+Example 2:
+
+Input: n = 3
+Output: 27
+Explanation: In binary, 1, 2, and 3 corresponds to "1", "10", and "11".
+After concatenating them, we have "11011", which corresponds to the decimal value 27.
+Example 3:
+
+Input: n = 12
+Output: 505379714
+Explanation: The concatenation results in "1101110010111011110001001101010111100".
+The decimal value of that is 118505380540.
+After modulo 109 + 7, the result is 505379714.
+
+
+Constraints:
+
+1 <= n <= 105
+"""
+class Solution:
+    def concatenatedBinary(self, n: int) -> int:
+        result = ''
+        for i in range(1,n+1):
+            result += "{0:b}".format(i)
+        return min(int(result,2), int(result,2) % (10**9 + 7))