Sum of elements (#7829)

Algorithm Analysis

Read the input numbers and find their sum.

Algorithm Implementation

Declare the working array.

double m[100];

Read the input array.

scanf("%d",&n);
for(i = 0; i < n; i++)
    scanf("%lf",&m[i]);

Find the sum $s$ of all numbers in the array.

s = 0;
for(i = 0; i < n; i++)
    s = s + m[i];

Output the desired sum.

printf("%.1lf\n",s);

Algorithm Implementation – Loop

#include <stdio.h>

int i, n;
double s, val;

int main(void)
{
    scanf("%d",&n);
    s = 0;
    for(i = 0; i < n; i++)
    {
        scanf("%lf",&val);
        s = s + val;
    }
    printf("%.1lf\n",s);
    return 0;
}

Algorithm Implementation – Vector

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

int i, n;
double s;
vector<double> m;

int main(void)
{
    scanf("%d", &n);
    // allocate memory for vector, resize it
    m.resize(n);
    // read array
    for (i = 0; i < n; i++)
        scanf("%lf", &m[i]);
    // find the sum of array elements
    s = 0;
    for (i = 0; i < n; i++)
        s = s + m[i];
    // print the answer
    printf("%.1lf\n", s);
    return 0;
}

Algorithm Implementation – Dynamic Memory Allocation, `malloc`

#include <stdio.h>
#include <malloc.h>

int i, n;
double s, *m;

int main(void)
{
    scanf("%d", &n);
    m = (double *)malloc(n * sizeof(double));
    for (i = 0; i < n; i++) // read array
        scanf("%lf", &m[i]);
    s = 0; // find the sum of array elements
    for (i = 0; i < n; i++)
        s = s + m[i];
    free(m);
    printf("%.1lf\n", s); // print the answer
    return 0;
}

Algorithm Implementation – Dynamic Memory Allocation, `calloc`

#include <stdio.h>
#include <malloc.h>

int i, n;
double s, *m;

int main(void)
{
    scanf("%d", &n);
    m = (double *)calloc(n, sizeof(double));
    for (i = 0; i < n; i++) // read array
        scanf("%lf", &m[i]);
    s = 0; // find the sum of array elements
    for (i = 0; i < n; i++)
        s = s + m[i];
    free(m);
    printf("%.1lf\n", s); // print the answer
    return 0;
}

Algorithm Implementation – Dynamic Memory Allocation, `new`

#include <stdio.h>

int i, n;
double s;
double *m;

int main(void)
{
    scanf("%d",&n);
    // allocate memory for array
    m = new double[n];
    // read array
    for(i = 0; i < n; i++)
        scanf("%lf",m+i); // m + i = &m[i]
    // find the sum of array elements
    s = 0;
    for(i = 0; i < n; i++)
        s = s + m[i];
    // print the answer
    printf("%.1lf\n",s);
    // deallocate the array memory
    delete[] m;
    return 0;
}

Algorithm Implementation – Using Files

When working with files in the e-olymp system, the following are used:

input.txt – input file;
output.txt – output file;

When submitting solutions with files, select the option "Solution uses files for reading and writing".

#include <stdio.h>

int i, n;
double s, m[100];

int main(void)
{
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    scanf("%d",&n);
    // read array
    for(i = 0; i < n; i++)
        scanf("%lf",&m[i]);
    // find the sum of array elements
    s = 0;
    for(i = 0; i < n; i++)
        s = s + m[i];
    // print the answer
    printf("%.1lf\n",s);
    return 0;
}

Algorithm Implementation - STL

We will use the accumulate function.

#include <cstdio>
#include <numeric>
using namespace std;

int i, n;
double s, *m;

int main(void)
{
    scanf("%d",&n);
    m = new double[n];
    for(i = 0; i < n; i++)
        scanf("%lf",&m[i]);
    s = accumulate(m,m+n,0.0);
    printf("%.1lf\n",s);
    return 0;
}

Java Implementation

public class Main
{
    public static void main(String[] args)
    {
        Scanner con = new Scanner(System.in);
        con.useLocale(Locale.US);
        int n = con.nextInt();
        double sum = 0;
        for (int i = 0; i < n; i++) 
        {
            double val = con.nextDouble();
            sum += val;
        }
        System.out.printf("%.1f",sum);
        con.close();
    }
}

Java Implementation – Custom Class

import java.util.*;

class Array
{
    private double[] m;
    private int size;

    public Array(int n)
    {
        size = n;
        m = new double[n];
    }

    public void set(int i, double value)
    {
        m[i] = value;  
    }

    public double getSum()
    {
        double s = 0;
        for(int i = 0; i < size; i++)
            s = s + m[i];
        return s;
    }
}

public class Main
{
    public static void main(String[] args)
    {
        Scanner con = new Scanner(System.in);
        con.useLocale(Locale.US);
        int n = con.nextInt();
        Array a = new Array(n);
        
        for (int i = 0; i < n; i++) 
            a.set(i,con.nextDouble());

        System.out.printf("%.1f",a.getSum());
        con.close();
    }
}

Python Implementation

n = int(input())
m = list(map(float,input().split()))
print(sum(m))