DSA/OptimalBST.cpp at main · SiddhantHargude/DSA · GitHub

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#include <iostream>
#define SIZE 10
using namespace std;

class optimal {
public:
    int p[SIZE];
    int q[SIZE];
    int a[SIZE];
    int w[SIZE][SIZE];
    int c[SIZE][SIZE];
    int r[SIZE][SIZE];
    int n;
    int front, rear, queue[20];

    optimal() {
        front = rear = -1;
    }
    void getdata();
    int minvalue(int, int);
    void OBST();
    void buildtree();
};

void optimal::getdata() {
    int i;
    cout << "\n Optimal Binary search tree";
    cout << "\n Enter the number of nodes :";
    cin >> n;
    cout << "\n Enter the data : \n";
    for (i = 1; i <= n; i++) {
        cout << "\n a[" << i << "]: ";
        cin >> a[i];
    }
    cout << "\n Enter probabilities for successful search \n";
    for (i = 1; i <= n; i++) {
        cout << "p[" << i << "]: ";
        cin >> p[i];
    }
    cout << "\n Enter probabilities for unsuccessful search \n";
    for (i = 1; i <= n; i++) {
        cout << "q[" << i << "]: ";
        cin >> q[i];
    }
}

int optimal::minvalue(int i, int j) {
    int m, k;
    int min = 32000;
    for (m = r[i][j - 1]; m <= r[i + 1][j]; m++) {
        if ((c[i][m - 1] + c[m][j]) < min) {
            min = c[i][m - 1] + c[m][j];
            k = m;
        }
    }
    return k;
}

void optimal::OBST() {
    int i, j, k, m;
    for (i = 0; i < n; i++) {
        w[i][i] = q[i];
        r[i][i] = c[i][i] = 0;
        w[i][i + 1] = q[i] + q[i + 1] + p[i + 1];
        r[i][i + 1] = i + 1;
        c[i][i + 1] = q[i] + q[i + 1] + p[i + 1];
    }
    w[n][n] = q[n];
    r[n][n] = c[n][n] = 0;
    for (m = 2; m <= n; m++) {
        for (i = 0; i <= n - m; i++) {
            j = i + m;
            w[i][j] = w[i][j - 1] + p[j] + q[j];
            k = minvalue(i, j);
            c[i][j] = w[i][j] + c[i][k - 1] + c[k][j];
            r[i][j] = k;
        }
    }
}

void optimal::buildtree() {
    int i, j, k;
    cout << "\n The optimal Binary search tree for given nodes is : \n";
    cout << "\n The root of this OBST is :" << r[0][n];
    cout << "\n The cost of this OBST is: " << c[0][n];
    cout << "\n\n Node \t Left child \t Right child";
    cout << "\n _____________________________________" << endl;
    queue[++rear] = 0;
    queue[++rear] = n;
    while (front != rear) {
        i = queue[++front];
        j = queue[++front];
        k = r[i][j];
        cout << "\n\t" << k;
        if (r[i][k - 1] != 0) {
            cout << "       " << r[i][k - 1];
            queue[++rear] = i;
            queue[++rear] = k - 1;
        } else {
            cout << "      ";
        }
        if (r[k][j] != 0) {
            cout << "         " << r[k][j];
            queue[++rear] = k;
            queue[++rear] = j;
        } else {
            cout << "          ";
        }
    }
    cout << endl;
}

int main() {
    optimal obj;
    obj.getdata();
    obj.OBST();
    obj.buildtree();
    return 0;
}