I'm trying to write a code which print the sum of odd and even numbers from a group of inputs, but it doesn't work and I think it's a null safety issue.
This is the code
void main() {
List numbers = [1, 2, 3, 4];
List odd = [];
List even = [];
for (int i = 0; i < numbers.length; i++) {
var z = numbers[i] % 2;
if (z == 0) {
even.add(numbers[i]);
} //end if
else {
odd.add(numbers[i]);
} //end else
} //end for loop
int sumOdd = 0;
int sumEven = 0;
for (int i = 0; i < odd.length; i++) {
sumOdd = sumOdd + odd[i];
}//end for
for (int i = 0; i < even.length; i++) {
sumEven = sumEven + even[i];
}//end for
print("sum of odds numbers = $sumOdd");
print("sum of even numbers = $sumEven");
} //end main
i think its because you not specify the type of list.
by default it will define as a list of number.
but int sumOdd = 0; you define as integer.
thats why you got error when run here : sumOdd = sumOdd + odd[i];
sumOdd is integer
odd[i] is number .
solution:
List<int> numbers = [1, 2, 3, 4];
List <int> even =[];
List<int> odd =[];
second solution
you can parse odd[i] to integer
Related
I still dont know weather I am allowed discuss Competetive Programming Doubts here, please let me know..
Can someone help me on this SPOJ question, I am getting wrong Answer:
https://www.spoj.com/problems/SPIKES/
I have tried all the test cases I could think of and the code always gives correct output.
Before posting it here, I also asked it in spoj forum but Its been two days, no one replies...
#include<bits/stdc++.h>
using namespace std;
// # = 35
// # = 64
// . = 46
// s = 115
// Using Dijkstra to find the path with minimum no. of Spikes
int n,m,j;
const int N = 100;
const int INF = 9;
vector<int> g[N];
int vis[N][N];
pair<int,int> dist[N][N];
vector<pair<int,int>> movements = {
{0,1},{0,-1},{1,0},{-1,0}
};
bool isvalid(int i, int j){
return i>=0 && j>=0 && i<n && j<m;
}
void bfs(int sourcei, int sourcej){
set<pair<int,pair<int,int>>> q;
q.insert({0,{sourcei,sourcej}});
dist[sourcei][sourcej] = {0,INF};
while(q.size()>0){
auto curr_v = *q.begin();
int curr_i = (curr_v.second).first;
int curr_j = (curr_v.second).second;
int spikes = curr_v.first;
q.erase(q.begin());
if(vis[curr_i][curr_j]) continue;
vis[curr_i][curr_j] = 1;
for(auto m : movements){
int child_i = curr_i + m.first;
int child_j = curr_j + m.second;
int spikec = spikes;
if(!isvalid(child_i,child_j)) continue;
if(g[child_i][child_j] == 115) spikec = spikes+1;
if(vis[child_i][child_j]) continue;
if(g[child_i][child_j]==35) continue;
if(dist[child_i][child_j].second > spikec){
dist[child_i][child_j] = {(dist[curr_i][curr_j].first +1),spikec};
q.insert({spikec , {child_i,child_j}});
}
}
}
}
int main(){
cin>>n>>m>>j;
int start_j,start_i;
int end_j,end_i;
for (int i = 0; i < N; ++i){
for (int j = 0; j < N; ++j){
dist[i][j].second = INF;
dist[i][j].first = 0;
}
}
for (int i = 0; i < n; ++i){
for (int j = 0; j < m; ++j){
char x; cin>>x;
g[i].push_back((int)x);
if(x=='#') {
start_i = i;
start_j = j;
}
if(x=='x'){
end_i = i;
end_j = j;
}
}
}
bfs(start_i,start_j);
// for (int i = 0; i < n; ++i){
// for (int j = 0; j < m; ++j){
// cout<<dist[i][j].first<<","<<dist[i][j].second<<" ";
// }cout<<endl;
// }
if(dist[end_i][end_j].second <= (int)j/2) cout<<"SUCCESS"<<endl;
else cout<<"IMPOSSIBLE"<<endl;
return 0;
}
May I know how to store the N prime numbers, which I got from for loop in an array in dart?
import 'dart:io';
void main() {
// print('enter a start number');
// int a = int.parse(stdin.readLineSync()!);
print('enter a number');
int b = int.parse(stdin.readLineSync());
print('this are prime numbers');
primenum(b);
var z = '';
}
primenum(b) {
String string = "";
int a = 2;
outerLoop:
for (int i = a; i <= b; i++) {
for (int x = 2; x <= i / a; x++) {
if (i % x == 0) {
continue outerLoop;
}
}
var z = i.toString();
// print(z);
var h = z;
// String str = '';
string = string + h;
}
List d = string.split('');
print(d);
}
Using the above code, I am able to get those numbers in List. But the double-digit numbers are splitting.
May I know How to solve the above task? using dart.
The way you're doing string.split is splitting the string into a list of each individual character. Instead, you can add each prime number to a List directly without doing string manipulation.
primenum(b) {
List<String> d;
int a = 2;
outerLoop:
for (int i = a; i <= b; i++) {
for (int x = 2; x <= i / a; x++) {
if (i % x == 0) {
continue outerLoop;
}
}
d.add(i.toString());
}
print(d);
}
What is the right syntax in dart for the below js code:
I am trying to create a function ArrayAddition(arr) take the array
of numbers stored in arr and return the string true if any combination of numbers
in the array can be added up to equal the largest number in the array, otherwise
return the string false. For example: if arr contains [4, 6, 23, 10, 1, 3] the
output should return true because 4 + 6 + 10 + 3 = 23.
function ArrayAddition(arr) {
arr.sort(function(a,b){return a - b});
var maxNum = arr.pop();
var tot = 0;
for (var i = 0; i < arr.length; i++){
tot += arr[i];
for (var j = 0; j < arr.length; j++){
if (i != j) {
tot += arr[j];
if (tot == maxNum) {
return true;
}
}
}
for (var k = 0; k < arr.length; k++) {
if (i != k) {
tot -= arr[k];
if (tot == maxNum) {
return true;
}
}
}
tot = 0;
}
return false;
}
So what is the rightt syntax for this in dart language?
It's almost the exact same code, just change the following lines:
function ArrayAddition(arr) {
to
bool ArrayAddition(List<int> arr) {
arr.sort(function(a,b){return a - b});
to
arr.sort((a, b) => a - b);
var maxNum = arr.pop();
to
var maxNum = arr.removeLast();
I am trying to solve 445. Add Two Numbers II from LeetCode where it is asked:
Given two non-empty linked lists representing two non-negative integers, add the two numbers and return it as a linked list. The most significant digit comes first and each of their nodes contain a single digit.
For some test cases, I am getting negative number from the sum method that I have implemented. I think it is impossible to get any negative digit in my code. Can you help me finding the bug?
Below is the code that I tried:
/**
* 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; }
* }
*/
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
//ListNode previous = null;
int len1 = 0;
int len2 = 0;
ListNode head1 = l1;
ListNode head2 = l2;
while(l1!=null){
len1++;
l1=l1.next;
}
while(l2!=null){
len2++;
l2=l2.next;
}
int sum=0;
if (len1 >= len2){
sum= sum(head1,head2,len1,len2);
}else{
sum= sum(head2,head1,len2,len1);
}
String sumString = "" + sum;
ListNode extraHead = new ListNode(1);
ListNode copy = extraHead;
for(int i = 0;i<sumString.length();i++){
ListNode bit = new ListNode(Integer.parseInt(String.valueOf(sumString.charAt(i))));//Integer.parseInt(String.valueOf(sumString.charAt(i)))
extraHead.next = bit;
extraHead = extraHead.next;
}
return copy.next;
}
public int sum(ListNode l1, ListNode l2, int len1, int len2){
int diff = 0;
int resLen = 0;
diff = len1 - len2;
resLen = len1;
int[] res = new int[resLen];
ListNode fast = l1;
ListNode slow = l2;
for(int count = 0; count<diff; count++){
res[count] = fast.val;
fast = fast.next;
}
for(int count = diff;count < res.length;count++){
res[count] = fast.val + slow.val;
fast=fast.next;
slow=slow.next;
}
int sum = 0;
for(int i = len1;i>0;i-- ){
sum = sum + res[len1-i] * (int)Math.pow(10,i-1);
}
return sum;
}
}
Here is the error message that I get:
Error Details
java.lang.NumberFormatException: For input string: "-"
at line 68, java.base/java.lang.NumberFormatException.forInputString
at line 648, java.base/java.lang.Integer.parseInt
at line 776, java.base/java.lang.Integer.parseInt
at line 41, Solution.addTwoNumbers
at line 54, __DriverSolution__.__helper__
at line 87, __Driver__.main
Here is the input causing the error:
[3,9,9,9,9,9,9,9,9,9]
[7]
I wrote this code to determine which numbers between two numbers someone types are prime and which are composite. The user types two numbers, e.g. 5 & 10, and in that case the program should output:
5 is prime
6 is not prime
7 is prime
8 is not prime
9 is not prime
10 is not prime
But it is not doing this correctly. For example, if the user enters 13 and 33, the output is that 13, 14, and 15 are prime, but all the other numbers are not. What's even more strange is that the results contradict each other. For example, if the user enters 10 and 20, the program outputs that all the numbers are not prime.
package more.basic.applications;
import java.util.Scanner;
public class MoreBasicApplications {
public static void main(String[] args)
{
//program to determine how many numbers between 2 numbers inclusive are prime, and how many are composite, as well as display them
int j = 2;
Scanner reader = new Scanner(System.in);
System.out.println("Please enter number 1, between 0 and 100: ");
int number = reader.nextInt();
boolean composite = false;
System.out.println("Please enter number 2, between 0 and 200: ");
int number2 = reader.nextInt();
int difference = number2 - number;
int[] array = new int[difference+1];
for (int i = 0; i < array.length; i++)
{
array[i] = number + i;
while (j <= Math.sqrt(array[i]))
{
if (array[i]%j == 0) {
composite = true;
}
j++;
}
if (composite == true) {
System.out.println (array[i] + " is not prime.");
}
else
{
System.out.println (array[i] + " is prime.");
}
}
}
It looks like you don't "reset" j back to 2 at the beginning of your for loop, so j keeps getting bigger and bigger.
for (int i = 0; i < array.length; i++) {
j = 2; // reset j back to 2.
array[i] = number + i;
while (j <= Math.sqrt(array[i])) {
if (array[i]%j == 0) {
composite = true;
}
j++;
}
if (composite == true) {
System.out.println (array[i] + " is not prime.")
} else {
System.out.println (array[i] + " is prime.");
}
}