thảo luận [Học Tập] Topic thuật toán

#include <iostream>
#include <fstream>
// implement these function
// ham doc gia tri N va X
void readNandX(int &N, int &X);
// ham dien cac gia tri vao mang A
void readAarray(int *A, int N);
// ham xuat i, j, k, t
void writeijkt(int i, int j, int k, int t);
// ham xuat impossible
void writeimposible(void);
void Sump4(void)
{
    int N, X;
    readNandX(N, X);
    int *A;
    A = new int[N];
    readAarray(A, N);
    // sau khi co du input dau vao, tien hanh tim 4 index
    for (int i = 0; i < (N - 3); i++)
    {
        for (int j = (i + 1); j < (N - 2); j++)
        {
            for (int k = (j + 1); k < (N - 1); k++)
            {
                for (int t = (k + 1); t < N; t++)
                {
                    if ((A + A[j] + A[k] + A[t]) == X)
                    {
                        // thoa man, ghi 4 index ra file roi out
                        writeijkt(i + 1, j + 1, k + 1, t + 1);
                        return;
                    }
                }
            }
        }
    }
    // new khong thoa man dieu kien, ghi impossible
    writeimposible();
}

#include <bits/stdc++.h>

using namespace std;
const int Max = 1000;
class MangTong
{
public:
    int l;
    int r;
    int tong;
};

void ReadData(int a[],int &n,int &x)
{
        cin >> n >> x;
        for(int i=0;i<n;i++)
            cin >> a[i];
}
void Sort(MangTong a[],int n)
{
    for(int i=0;i<n-1;i++)
        for(int j=i+1;j<n;j++)
            if(a[i].tong>a[j].tong){
                MangTong t = a[i];
                a[i] = a[j];
                a[j] = t;
            }
}
bool Check(MangTong a,MangTong b)
{
    if(a.l == b.l || a.r == b.r || a.l == b.r || a.r ==b.l)
        return false;
    return true;
}
void Find(int a[],int n,int x)
{
    int Size = n*(n-1)/2;
    MangTong s[Size];
    int k = 0;
    for(int i = 0;i<n-1;i++)
        for(int j = i+1;j<n;j++)
        {
            s[k].tong = a[i] + a[j];
            s[k].l = i;
            s[k].r = j;
            k++;
        }
    Sort(s,Size);
    int i = 0;
    int j = Size -1;
    while(i<j)
    {
        if(s[i].tong + s[j].tong == x && Check(s[i],s[j]))
        {
            cout << s[i].l+1 << " " << s[i].r+1 << " " << s[j].l+1 <<" " << s[j].r+1;
            break;
        }
        else if(s[i].tong + s[j].tong < x)
            i++;
        else j--;
    }
}
int main()
{
    int a[Max];
    int n,x;
    ReadData(a,n,x);
    Find(a,n,x);
    return 0;
}

#include <bits/stdc++.h>
using namespace std;

struct elements{
    int value;
    int index;
};

int main()
{
    iostream::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    vector<elements> arr;
    elements temp;
    for (int i = 1; i <= n; i++)
    {
        cin >> temp.value;
        temp.index = i;
        arr.push_back(temp);
    }

    sort(arr.begin(), arr.end(), [](elements a, elements b){
        return a.value > b.value;
    });
   
    for (int i = 0; i < n - 1; ++i)
        for (int j = i + 1; j < n - 1; ++j)
        {
            int l = j + 1, r = n - 1;
            while (l < r)
            {  
                int sum = arr[i].value + arr[j].value + arr[l].value + arr[r].value;
                if (sum == k)
                {
                    vector<int> output;
                    output.push_back(arr[i].index);
                    output.push_back(arr[j].index);
                    output.push_back(arr[l].index);
                    output.push_back(arr[r].index);
                    sort(output.begin(), output.end());
                    for (auto voz : output)
                        cout << voz << " ";
                    return 0;
                }
                else if (sum < k)
                    l++;
                else
                    r--;
            }
        }
    cout << "IMPOSSIBLE" << endl;
    return 0;
}