Package g1301_1400.s1375_number_of_times_binary_string_is_prefix_aligned

Class Solution

java.lang.Object
g1301_1400.s1375_number_of_times_binary_string_is_prefix_aligned.Solution
public class Solution extends Object
1375 - Number of Times Binary String Is Prefix-Aligned\. Medium You have a **1-indexed** binary string of length `n` where all the bits are `0` initially. We will flip all the bits of this binary string (i.e., change them from `0` to `1`) one by one. You are given a **1-indexed** integer array `flips` where `flips[i]` indicates that the bit at index `i` will be flipped in the ith step. A binary string is **prefix-aligned** if, after the ith step, all the bits in the **inclusive** range `[1, i]` are ones and all the other bits are zeros. Return _the number of times the binary string is **prefix-aligned** during the flipping process_. **Example 1:** **Input:** flips = [3,2,4,1,5] **Output:** 2 **Explanation:** The binary string is initially "00000". After applying step 1: The string becomes "00100", which is not prefix-aligned. After applying step 2: The string becomes "01100", which is not prefix-aligned. After applying step 3: The string becomes "01110", which is not prefix-aligned. After applying step 4: The string becomes "11110", which is prefix-aligned. After applying step 5: The string becomes "11111", which is prefix-aligned. We can see that the string was prefix-aligned 2 times, so we return 2. **Example 2:** **Input:** flips = [4,1,2,3] **Output:** 1 **Explanation:** The binary string is initially "0000". After applying step 1: The string becomes "0001", which is not prefix-aligned. After applying step 2: The string becomes "1001", which is not prefix-aligned. After applying step 3: The string becomes "1101", which is not prefix-aligned. After applying step 4: The string becomes "1111", which is prefix-aligned. We can see that the string was prefix-aligned 1 time, so we return 1. **Constraints:** * `n == flips.length` * 1 <= n <= 5 * 104 * `flips` is a permutation of the integers in the range `[1, n]`.

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • numTimesAllBlue

      public int numTimesAllBlue(int[] flips)