Rust Leetcode 记录

2022-03-23

217. 存在重复元素

use std::collections::HashMap;
impl Solution {
    pub fn contains_duplicate(nums: Vec<i32>) -> bool {
        let mut hmap = HashMap::new();
        for num in nums {
            match hmap.get(&num) {
                Some(x) => {
                    return true;
                },
                None => {
                    hmap.insert(num,true);
                },
            }
        }
        return false;
    }
}

2022-04-06

53. 最大子数和

impl Solution {
    pub fn max_sub_array(nums: Vec<i32>) -> i32 {
        use std::cmp::max;
        let mut ans = nums[0];
        let mut sum = 0;
        for x in nums {
            sum = x + max(sum, 0);
            ans = max(ans, sum);
        }
        return ans;
    }
}

2022-04-11

136.只出现一次的数字

impl Solution {
    pub fn single_number(nums: Vec<i32>) -> i32 {
        use std::collections::HashMap;
        let mut haveNum = HashMap::new();
        for num in &nums {
            let count = haveNum.entry(num).or_insert(0);
            *count += 1;
        }
        for num in &nums {
            let count = haveNum.entry(num).or_insert(0);
            if *count == 1 {
                return *num;
            }
        }
        return 0;
    }
}

2022-04-12

(169. 多数元素)[https://leetcode-cn.com/problems/majority-element/]

impl Solution {
    pub fn majority_element(nums: Vec<i32>) -> i32 {
        use std::collections::HashMap;
        let mut haveNum = HashMap::new();
        for num in &nums {
            let count = haveNum.entry(num).or_insert(0);
            *count += 1;
        }
        for num in &nums {
            let count = haveNum.entry(num).or_insert(0);
            if *count > nums.len()/2 {
                return *num;
            }
        }
        return 0;
    }
}