Hot100(golang)

记录一下经典leetcode hot100的解题思路和题解

哈希

1. 两数之和

题解

package main

import (
    "fmt"
    "reflect"
)

func twoSum(nums []int, target int) (ans []int) {
    mp := map[int]int{}

    for idx, num := range nums {
        if i, ok := mp[target-num]; ok {
            ans = []int{i, idx}
        }
        mp[num] = idx
    }

    return ans
}

func main() {
    testCases := []struct {
        nums   []int
        target int
        ans    []int
    }{
        {nums: []int{2, 7, 11, 15}, target: 9, ans: []int{0, 1}},
        {nums: []int{3, 2, 4}, target: 6, ans: []int{1, 2}},
        {nums: []int{3, 3}, target: 6, ans: []int{0, 1}},
    }

    for _, t := range testCases {
        fmt.Println(reflect.DeepEqual(twoSum(t.nums, t.target), t.ans))
    }
}

49. 字母异位词分组

题解

package main

import (
    "fmt"
    "reflect"
    "slices"
)

func groupAnagrams(strs []string) [][]string {
    mp := map[string][]string{}

    for _, str := range strs {
        s := []byte(str)
        slices.Sort(s)
        mp[string(s)] = append(mp[string(s)], str)
    }

    ans := make([][]string, 0, len(mp))

    for i := range mp {
        ans = append(ans, mp[i])
    }

    return ans
}

func main() {
    testCases := []struct {
        strs []string
        ans  [][]string
    }{
        {
            []string{"eat", "tea", "tan", "ate", "nat", "bat"},
            [][]string{
                {"eat", "tea", "ate"},
                {"tan", "nat"},
                {"bat"},
            },
        },
        {
            []string{""},
            [][]string{
                {""},
            },
        },
        {
            []string{"a"},
            [][]string{
                {"a"},
            },
        },
    }

    for _, t := range testCases {
        fmt.Println(reflect.DeepEqual(groupAnagrams(t.strs), t.ans))
    }
}

128. 最长连续序列

题解

package main

import "fmt"

func longestConsecutive(nums []int) int {
    ans := 0
    mp := map[int]bool{}

    for _, num := range nums {
        mp[num] = true
    }

    for i := range mp {
        if mp[i-1] == true {
            continue
        }
        cnt := 1

        for mp[i+1] == true {
            i += 1
            cnt += 1
        }

        ans = max(ans, cnt)
    }

    return ans
}

func main() {
    testCases := []struct {
        nums []int
        ans  int
    }{
        {[]int{100, 4, 200, 1, 3, 2}, 4},
        {[]int{0, 3, 7, 2, 5, 8, 4, 6, 0, 1}, 9},
        {[]int{1, 0, 1, 2}, 3},
    }

    for _, t := range testCases {
        fmt.Println(longestConsecutive(t.nums) == t.ans)
    }
}