KoichiSugi

//naive
public static void miniMaxSum(List < Long > arr) {
    // Write your code here
    long sum = 0;
    List < Long > arr2 = new ArrayList < Long > ();
    for (int i = 0; i < arr.size(); i++) {
        for (int j = 0; j < arr.size(); j++) {
            if (j == i) {
                continue;
            }

KoichiSugi

func isPalindrome(x int) bool {
    str := strconv.Itoa(x)
	if x < 0 {
		return false
	}
	for i := 0; i < len(str)/2; i++ {
		length := len(str) - 1
		if str[i] != str[length-i] {
			fmt.Println(str[i])
			fmt.Println(str[length-i])

KoichiSugi

package main

import (
	"fmt"
	"sync"
)

type Factorial struct {
	original int
	fNum     int

KoichiSugi

func twoSum(nums []int, target int) []int {

	m := make(map[int]int)
	for i, e := range nums {
		_, ok := m[e]
		if ok {
			return []int{m[nums[i]], i}
		} else {

			m[target-e] = i

KoichiSugi

package main

import "fmt"

func main() {
	arr := []rune{'a', 'b', 'a', 'a', 'b', 'c', 'd', 'e', 'f', 'c', 'a', 'b', 'a', 'd'}
	m := make(map[rune]int)
	for _, e := range arr {
		_, ok := m[e] //search through map with a rune
		if ok {

KoichiSugi

//Time Complexity:  O(n) linear time
public class SumNumbers {

	public static void main(String[] args) {
		int[] ans = comp(new int[] { 0, 2, 4, 5, 6 }, 99);
		if (ans == null) {
			System.out.println("Not found");
		} else {
			for (int i : ans) {
				System.out.println(i);

KoichiSugi

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */

KoichiSugi

class Solution {
    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<Character>();
        if (s.length() % 2 != 0 ) return false;
        
        for (char c : s.toCharArray()) {
            if (c == '{' || c == '['  || c == '(') {
                stack.push(c);
            }else if(c == '}' && !stack.isEmpty() && stack.peek() == '{'){
                stack.pop();

KoichiSugi

class Solution {
    public String longestCommonPrefix(String[] strs) {
        String prefix = strs[0];
        for (int i = 1; i <= strs.length - 1; i++) {
            //first compare 1st element and 2nd element
            prefix = commonPrefixUtil(prefix, strs[i]);
        }

        return prefix;
    }

KoichiSugi

class Solution {
    public int romanToInt(String s) {
        int[] num = new int[s.length()];
        int sum = 0;
        for (int i = 0; i < s.length(); i++) {
            num[i] += getNumber(s.charAt(i));
        }

        for (int i = 0; i < num.length - 1; i++) {