LeetCode刷题--点滴记录001

Posted 2022-06-06 鲁棒最小二乘支持向量机

1. 两数之和

要求

给定一个整数数组 nums 和一个整数目标值 target，请你在该数组中找出 和为目标值 target 的那 两个 整数，并返回它们的数组下标。

解题— —暴力破解

C++版本

#include <iostream>
using namespace std;
#include <vector>

void printVector(vector<int>& v)

    for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
    
        cout << *it << " ";
    
    cout << endl;


class Solution 

public:
	vector<int> twoSum(vector<int>& nums, int target)
	
        vector<int> ans;
        for (int i = 0; i < nums.size(); i++)
        
            for (int j = i + 1; j < nums.size(); j++)
            
                if (nums[i] + nums[j] == target)
                
                    ans.push_back(i);
                    ans.push_back(j);
                    return ans;
                
            
        
        return ans;
    ;
;
void test01()

    Solution s;
    vector<int> nums;
    nums.push_back(2);
    nums.push_back(7);
    nums.push_back(11);
    nums.push_back(15);
    printVector(nums);

    int target = 9;

    vector<int> result;
    result = s.twoSum(nums,target);
    printVector(result);

void test02()

    Solution s;
    vector<int> nums;
    nums.push_back(3);
    nums.push_back(2);
    nums.push_back(4);
    printVector(nums);

    int target = 6;

    vector<int> result;
    result = s.twoSum(nums, target);
    printVector(result);

void test03()

    Solution s;
    vector<int> nums;
    nums.push_back(3);
    nums.push_back(3);
    printVector(nums);

    int target = 6;

    vector<int> result;
    result = s.twoSum(nums, target);
    printVector(result);

int main()

    test01();
    cout << "------------------" << endl;
    test02();
    cout << "------------------" << endl;
    test03();

	system("pause");
	return 0;

Python版本

class Solution:
    def twoSum(self,nums,target):
        for i in range(0,len(nums)):
            for j in range(i+1,len(nums)):
                if nums[i]+nums[j] == target:
                    return [i,j]

def test01():
    nums = [2,7,11,15]
    target = 9
    s = Solution()
    print(s.twoSum(nums,target))
    
def test02():
    nums = [3,2,4]
    target = 6
    s = Solution()
    print(s.twoSum(nums,target))
    
def test03():
    nums = [3,3]
    target = 6
    s = Solution()
    print(s.twoSum(nums,target))
    
            
if __name__=="__main__":
    test01()
    print("--------------")
    test02()
    print("--------------")
    test03()

Java版本

package com.hailei_01;

public class TwoSum 
    public static void main(String[] args) 
        int[] nums1 = 2,7,11,15;
        int target1 = 9;
        int[] result1 = twoSum(nums1, target1);
        System.out.println(arrayToString(result1));
        System.out.println("-------------------");
        int[] nums2 = 3,2,4;
        int target2 = 6;
        int[] result2 = twoSum(nums2, target2);
        System.out.println(arrayToString(result2));
        System.out.println("-------------------");
        int[] nums3 = 3,3;
        int target3 = 6;
        int[] result3 = twoSum(nums3, target3);
        System.out.println(arrayToString(result3));
    

    public static int[] twoSum(int[] nums, int target) 
        int []ans=new int[2];
        for(int i=0;i<nums.length;i++)
            for(int j=(i+1);j<nums.length;j++)
                if(nums[i]+nums[j]==target)
                    ans[0]=i;
                    ans[1]=j;
                    return ans;
                
            
        
        return ans;
    

    //把数组中的元素按照指定规则组成一个字符串
    public static String arrayToString(int[] arr) 
        StringBuilder sb = new StringBuilder();
        sb.append("[");
        for (int i = 0; i < arr.length; i++) 
            if (i == arr.length - 1) 
                sb.append(arr[i]);
             else 
                sb.append(arr[i]).append(",");
            
        
        sb.append("]");
        String s = sb.toString();
        return s;
    

解题— —升级

C++版本

#include <iostream>
using namespace std;
#include <vector>
#include <map>

void printVector(vector<int>& v)

    for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
    
        cout << *it << " ";
    
    cout << endl;


class Solution 
public:
    vector<int> twoSum(vector<int>& nums, int target) 
        map<int, int> a;
        vector<int> b(2, -1);
        for (int i = 0; i < nums.size(); i++)
            a.insert(pair<int,int>(nums[i], i));
        for (int i = 0; i < nums.size(); i++)
        
            if (a.count(target - nums[i]) > 0 && (a[target - nums[i]] != i))
            
                b[0] = i;
                b[1] = a[target - nums[i]];
                break;
            
        
        return b;
    ;
;

void test01()

    Solution s;
    vector<int> nums;
    nums.push_back(2);
    nums.push_back(7);
    nums.push_back(11);
    nums.push_back(15);
    printVector(nums);

    int target = 9;

    vector<int> result;
    result = s.twoSum(nums,target);
    printVector(result);

void test02()

    Solution s;
    vector<int> nums;
    nums.push_back(3);
    nums.push_back(2);
    nums.push_back(4);
    printVector(nums);

    int target = 6;

    vector<int> result;
    result = s.twoSum(nums, target);
    printVector(result);

void test03()

    Solution s;
    vector<int> nums;
    nums.push_back(3);
    nums.push_back(3);
    printVector(nums);

    int target = 6;

    vector<int> result;
    result = s.twoSum(nums, target);
    printVector(result);

int main()

    test01();
    cout << "------------------" << endl;
    test02();
    cout << "------------------" << endl;
    test03();

	system("pause");
	return 0;

Python版本

class Solution:
    def twoSum(self, nums, target):
        hashmap = 
        for ind,num in enumerate(nums):
            hashmap[num] = ind
        for i,num in enumerate(nums):
            j = hashmap.get(target - num)
            if j is not None and i!=j:
                return [i,j]         

def test01():
    nums = [2,7,11,15]
    target = 9
    s = Solution()
    print(s.twoSum(nums,target))
    
def test02():
    nums = [3,2,4]
    target = 6
    s = Solution()
    print(s.twoSum(nums,target))
    
def test03():
    nums = [3,3]
    target = 6
    s = Solution()
    print(s.twoSum(nums,target))
    
            
if __name__=="__main__":
    test01()
    print("--------------")
    test02()
    print("--------------")
    test03()

Java版本

package com.hailei_02;

import java.util.HashMap;

public class TwoSum 
    public static void main(String[] args) 
        int[] nums1 = 2,7,11,15;
        int target1 = 9;
        int[] result1 = twoSum(nums1, target1);
        System.out.println(arrayToString(result1));
        System.out.println("-------------------");
        int[] nums2 = 3,2,4;
        int target2 = 6;
        int[] result2 = twoSum(nums2, target2);
        System.out.println(arrayToString(result2));
        System.out.println("-------------------");
        int[] nums3 = 3,3;
        int target3 = 6;
        int[] result3 = twoSum(nums3, target3);
        System.out.println(arrayToString(result3));
    

    public static int[] twoSum(int[] nums, int target) 

        int[] arr=new int[2];
        HashMap<Integer,Integer> map=new HashMap<Integer,Integer>();
        for(int i=0;i<nums.length;i++以上是关于LeetCode刷题--点滴记录001的主要内容，如果未能解决你的问题，请参考以下文章
 
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