added problem 1680

Author: SHA65536

problems/problem1680/binary_concat.go

@@ -0,0 +1,29 @@
+package problem1680
+
+/*
+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.
+*/
+
+const MOD = 1000000007
+
+func concatenatedBinary(n int) int {
+	var res, max, size int
+	// size is the current length of the binary number
+	// max is the maximal number of size binary length
+	max, size = 1, 1
+	for i := 1; i <= n; i++ {
+		// need to displace the result by the size of the next number
+		res <<= size
+		// and place the current number at the start
+		res |= i
+		// if next number will be longer
+		if i == max {
+			// adjust max and size
+			max <<= 1
+			max++
+			size++
+		}
+		res %= MOD
+	}
+	return res
+}

problems/problem1680/binary_concat_test.go

@@ -0,0 +1,31 @@
+package problem1680
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type Result struct {
+	Input    int
+	Expected int
+}
+
+var Results = []Result{
+	{1, 1},
+	{3, 27},
+	{12, 505379714},
+	{10000, 356435599},
+	{100000, 757631812},
+}
+
+func TestConcatBinaryConsecutive(t *testing.T) {
+	assert := assert.New(t)
+
+	for _, res := range Results {
+		want := res.Expected
+		got := concatenatedBinary(res.Input)
+		assert.Equal(want, got, fmt.Sprintf("%+v", res))
+	}
+}

readme.md

@@ -169,6 +169,7 @@ Each problem is in it's own directory, with test files. There are helper package
 | 1642 | [Furthest Building You Can Reach](https://leetcode.com/problems/furthest-building-you-can-reach) | [My Solution](./problems/problem1642) | ✅ |
 | 1647 | [Minimum Deletions to Make Character Frequencies Unique](https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique) | [My Solution](./problems/problem1647) | ✅ |
 | 1658 | [Minimum Operations to Reduce X to Zero](https://leetcode.com/problems/minimum-operations-to-reduce-x-to-zero) | [My Solution](./problems/problem1658) | ✅ |
+| 1680 | [Concatenation of Consecutive Binary Numbers](https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers) | [My Solution](./problems/problem1680) | ✅ |
 | 1689 | [Partitioning Into Minimum Number Of Deci-Binary Numbers](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers) | [My Solution](./problems/problem1689) | ✅ |
 | 1695 | [Maximum Erasure Value](https://leetcode.com/problems/maximum-erasure-value) | [My Solution](./problems/problem1695) | ✅ |
 | 1696 | [Jump Game VI](https://leetcode.com/problems/jump-game-vi) | [My Solution](./problems/problem1696) | ✅ |