Submission #59945745

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Source Code Expand

import java.io.*;
import java.util.*;
import java.util.function.Function;

public class Main
{
    static class FastReader { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() 
        { 
            br = new BufferedReader(new InputStreamReader(System.in)); 
        }
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) { 
                try { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException e) { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() { return Integer.parseInt(next()); } 
  
        long nextLong() { return Long.parseLong(next()); } 
  
        double nextDouble() { return Double.parseDouble(next()); } 

        int[] nextIntArray(int n)
        {
            int[] ans = new int[n];
            for(int i = 0; i < n; i++)
                ans[i] = nextInt();
            return ans;
        }

        Integer[] nextIntegerArray(int n)
        {
            Integer[] ans = new Integer[n];
            for(int i = 0; i < n; i++)
                ans[i] = nextInt();
            return ans;
        }

        long[] nextLongArray(int n)
        {
            long[] ans = new long[n];
            for(int i = 0; i < n; i++)
                ans[i] = nextLong();
            return ans;
        }

        String[] nextStringArray(int n)
        {
            String[] ans = new String[n];
            for(int i = 0; i < n; i++)
                ans[i] = next();
            return ans;
        }
  
        String nextLine() 
        { 
            String str = ""; 
            try { 
                if(st.hasMoreTokens()){ 
                    str = st.nextToken("\n"); 
                } 
                else{ 
                    str = br.readLine(); 
                } 
            } 
            catch (IOException e) { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    }
 
    static final int mod = (int)(1e9) + 7;
    static final long INF = (long)(1e18);
    static final int INF_INT = (int)(1e9);
 
    private static int gcd(int a, int b)
    {
        if(a % b == 0)
            return b;
        return gcd(b, a % b);
    }

    static class TreeNode
    {
        int start, end;
        TreeNode left, right;
        int len;
 
        TreeNode(int a, int b)
        {
            set(a, b);
            left = right = null;
        }
 
        void set(int a, int b)
        {
            start = a;
            end = b;
            len = end - start + 1;
        }
    }
 
    static class Pair
    {
        int dest;
        long distance;
        Pair(int a, long b)
        {
            dest = a;
            distance = b;
        }
 
        public String toString()
        {
            return "(" + dest + ", " + distance + ")";
        }
    }
    
    static class Slope
    {
        int n, d;
        Slope(int a, int b)
        {
            n = a;
            d = b;
            if(d == 0)
                n = 1;
            else if(n == 0)
                d = 1;
            else
            {
                int hcf = gcd(n, d);
                n /= hcf;
                d /= hcf;
            }
        }

        public double slope()
        {
            return (double)n / d;
        }

        public boolean equals(Slope ob)
        {
            return n == ob.n && d == ob.d;
        }

        public String toString()
        {
            return String.format("(%d, %d)", n, d);
        }
    }

    static class DSU
    {
        int n;
        int[] parent;
        int[] size;

        public DSU(int _n)
        {
            n = _n;
            parent = new int[n];
            size = new int[n];
            for(int i = 0; i < n; i++)
            {
                parent[i] = i;
                size[i] = 1;
            }
        }

        public int findParent(int node)
        {
            if(node == parent[node])
                return node;
            return parent[node] = findParent(parent[node]);
        }

        public void union(int u, int v)
        {
            int rootU = findParent(u), rootV = findParent(v);
            if(rootU != rootV)
            {
                if(rootU < rootV)
                {
                    parent[rootV] = rootU;
                    size[rootU] += size[rootV];
                    size[rootV] = 0;
                }
                else
                {
                    parent[rootU] = rootV;
                    size[rootV] += size[rootU];
                    size[rootU] = 0;
                }
            }
        }

        public boolean same(int u, int v)
        {
            return findParent(u) == findParent(v);
        }
    }
    
    static Long[][] dp;
    static int[][] trace;
    static Function<Integer, Integer> f1;

    public static void main(String args[]) throws IOException
    {
        FastReader fr = new FastReader();
        // Scanner fr = new Scanner(System.in);
        // Scanner fr = new Scanner(new File("C:\\Users\\ykgup\\Downloads\\test_input.txt"));
        // int _t = fr.nextInt();
        int _t = 1;
        // int _case = 1;
        StringBuilder _v = new StringBuilder();
        PrintWriter out = new PrintWriter(System.out);
        while(_t-- > 0)
        {
            int n = fr.nextInt();
            // n = 5
            // positions = [1, 2, 3, 4, 5]
            // candies = [1, 2, 3, 4, 5]
            // ans = 1 + 2 + 3 + 4 + 5
            // a_i = x
            // a_{i+1} = x+1
            // AP: a_0 = 1, d = 1
            // S_n = (n / 2) * (2 * a_0 + (n - 1) * d)
            // S_5 = (5 / 2) * (2 * 1 + (5 - 1) * 1)
            // S_5 = 2.5 * (2 + 4) = 2.5 * 6 = 15
            // S_5 = 1 + 2 + 3 + 4 + 5 = 15
            // S_n = (n / 2) * (2 * 1 + (n - 1) * 1) = (n / 2) * (2 + n - 1) = (n / 2) * (n+1)
            // S_n = n * (n+1) / 2
            _v.append(n * (n+1) / 2);
            _v.append("\n");
            // _v.append("Case");
            // _v.append(" ");
            // _v.append(_case++);
            // _v.append(": ");
        }
        out.print(_v);
        out.flush();
    }
}

Submission Info

Judge Result