package com.nianxi;

import org.junit.jupiter.api.Test;

import java.util.Arrays;

/**
 * @author Jie.
 * @description: TODO 两数之和
 * @date 2025/4/8
 * @version: 1.0
 */
public class LeetCode1Test {
    @Test
    public void test() {
        int[] nums = {3,2,4};
        int target = 6;
        System.out.println(Arrays.toString(twoSum(nums, target)));
    }

    public int[] twoSum(int[] nums, int target) {
        int length = nums.length;
        for (int i = 0; i < length; i++) {
            for (int j = i + 1; j < length; j++) {
                if (i != j && (nums[i] + nums[j]) == target) {
                    return new int[]{i, j};
                }
            }
        }
        return null;
    }
}

package com.nianxi;

import org.junit.jupiter.api.Test;

/**
 * @author Jie.
 * @description: TODO 整数反转
 * @date 2025/4/8
 * @version: 1.0
 */
public class LeetCode2Test {
    @Test
    public void test() {
        int x = -123;
        System.out.println(reverse(x));
    }

    public int reverse(int x) {
        StringBuilder res = new StringBuilder();
        String temp = x + res.toString();
        //1.判断是否为负数
        String fs = "";
        if (temp.startsWith("-")) {
            fs = "-";
            temp = temp.substring(1);
        }
        //2.进行反转
        for (int i = temp.length() - 1; i >= 0; i--) {
            res.append(temp.charAt(i));
        }
        //3.返回结果
        try {
            return Integer.parseInt(fs + res);
        } catch (Exception e) {
            return 0;
        }
    }
}

package com.nianxi;

import org.junit.jupiter.api.Test;

/**
 * @author Jie.
 * @description: TODO 回文数
 * @date 2025/4/9
 * @version: 1.0
 */
public class LeetCode3Test {
    @Test
    public void test() {
        int x = 121;
        System.out.println(isPalindrome(x));
    }

    public boolean isPalindrome(int x) {
        //1.判断是否小于0
        if(x < 0) {
            return false;
        }
        //2.获取比较次数
        String temp = x + "";
        int i = temp.length() / 2;
        for (int j = 0; j < i; j++) {
            if(temp.charAt(j) != temp.charAt(temp.length() - 1  - j)){
                return false;
            }
        }
        return true;
    }
}

package com.nianxi;

import org.junit.jupiter.api.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @author Jie.
 * @description: TODO 罗马数字转整数
 * @date 2025/4/9
 * @version: 1.0
 */
public class LeetCode4Test {
    @Test
    public void test() {
        String s = "III";
        System.out.println(romanToInt(s));
    }

    public int romanToInt(String s) {
        Map<Character, Integer> symbolValues = new HashMap<Character, Integer>() {{
            put('I', 1);
            put('V', 5);
            put('X', 10);
            put('L', 50);
            put('C', 100);
            put('D', 500);
            put('M', 1000);
        }};
        int ans = 0;
        int n = s.length();
        for (int i = 0; i < n; ++i) {
            int value = symbolValues.get(s.charAt(i));
            if (i < n - 1 && value < symbolValues.get(s.charAt(i + 1))) {
                ans -= value;
            } else {
                ans += value;
            }
        }
        return ans;
    }
}

package com.nianxi;

import org.junit.jupiter.api.Test;

/**
 * @author Jie.
 * @description: TODO 两整数相加
 * @date 2025/4/9
 * @version: 1.0
 */
public class LeetCode5Test {
    @Test
    public void test() {
        int num1 = 10;
        int num2 = 5;
        System.out.println(sum(num1,num2));
    }

    public int sum(int num1, int num2) {
        return num1 + num2;
    }
}