137. Single Number II
Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it.
Example 1:
Input: nums = [2,2,3,2] Output: 3
Example 2:
Input: nums = [0,1,0,1,0,1,99] Output: 99
Constraints:
1 <= nums.length <= 3 * 104-231 <= nums[i] <= 231 - 1- Each element in
numsappears exactly three times except for one element which appears once.
Follow up: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
Rust Solution
struct Solution;
impl Solution {
fn single_number(nums: Vec<i32>) -> i32 {
let mut once = 0;
let mut twice = 0;
for x in nums {
once = !twice & (once ^ x);
twice = !once & (twice ^ x);
}
once
}
}
#[test]
fn test() {
let nums = vec![2, 2, 3, 2];
let res = 3;
assert_eq!(Solution::single_number(nums), res);
let nums = vec![0, 1, 0, 1, 0, 1, 99];
let res = 99;
assert_eq!(Solution::single_number(nums), res);
}
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