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1.fibonacci_iterative.cpp

@@ -0,0 +1,23 @@
+#include<iostream>
+using namespace std;
+typedef long long ll;
+void printFibonacciNumbers(int n){
+    if(n>=0)cout<<0<<" ";
+    if(n>=1)cout<<1<<" ";
+    int prev2=0,prev1=1;
+    for(int i=2;i<n;i++){
+        int curr=prev2+prev1;
+        prev2=prev1;
+        prev1=curr;
+        cout<<curr<<" ";
+    }
+    return;
+}
+int main(){
+    int n;
+    cout<<"Enter Number"<<endl;
+    cin>>n;
+    printFibonacciNumbers(n);
+    return 0;
+
+}

1.fibonacci_recursive.cpp

@@ -0,0 +1,20 @@
+#include<include>
+using namespace std;
+typedef long long ll;
+int func(int n,vector<int>&dp){
+    if(dp[n]!=-1)return dp[n];
+    if(n==0 || n==1)return n;
+    int num=func(n-1,dp)+func(n-2,dp);
+    return dp[n]=num;
+}
+int main(){
+    int n;
+    cout<<"Enter Number"<<endl;
+    cin>>n;
+    vector<int>dp(n+1,-1);
+    for(int i=0;i<n;i++){
+        int num=func(i,dp);
+        cout<<num<<" ";
+    }
+    return 0;
+}

2.huffmanCoding.cpp

@@ -0,0 +1,66 @@
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+
+class Node{
+    public:
+    char data;
+    int freq;
+    Node *left,*right;
+    Node(char data,int freq){
+        this->data=data;
+        this->freq=freq;
+        left=right=NULL;
+    }
+};
+
+class cmp{
+    public:
+    bool operator()(Node* a,Node* b){
+        return a->freq>b->freq;
+    }
+};
+
+void printTree(Node *head,string str=""){
+    if(head==NULL)return;
+    if(head->left==NULL && head->right==NULL){
+        cout<<head->data<<" -> "<<str<<endl;
+        return;
+    }
+    printTree(head->left,str+"0");
+    printTree(head->right,str+"1");
+}
+
+Node* buildTree(vector<char>&arr,vector<int>&frequency){
+    priority_queue<Node*,vector<Node*>,cmp>pq;
+    for(int i=0;i<arr.size();i++){
+        pq.push(new Node(arr[i],frequency[i]));
+    }
+    while(pq.size()>1){
+        Node *a=pq.top();
+        pq.pop();
+        Node *b=pq.top();
+        pq.pop();
+        Node *c=new Node('$',a->freq+b->freq);
+        c->left=a;
+        c->right=b;
+        pq.push(c);
+    }
+    return pq.top();
+}
+
+int main(){
+    int n;
+    cin>>n;
+    vector<char>arr(n);
+    vector<int>frequency(n);
+    for(int i=0;i<n;i++){
+        cin>>arr[i];
+    }
+    for(int i=0;i<n;i++){
+        cin>>frequency[i];
+    }
+    Node *head=buildTree(arr,frequency);
+    printTree(head);
+    return 0;
+}

3.fractionalKnapsack.cpp

@@ -0,0 +1,42 @@
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+class Item{
+    public:
+    int value;
+    int weight;
+};
+
+bool cmp(Item a,Item b){
+    double r1=(double)a.value/(double)a.weight;
+    double r2=(double)b.value/(double)b.weight;
+    return r1>r2;
+}
+
+double fractionalKnapsack(vector<Item>items,int W){
+    sort(items.begin(),items.end(),cmp);
+    double mx=0;
+    for(int i=0;i<items.size();i++){
+        if(items[i].weight<=W){
+            mx+=items[i].value;
+            W-=items[i].weight;
+        }
+        else{
+            mx+=(items[i].value/(double)items[i].weight)*(double)W;
+            break;
+        }
+    }
+    return mx;
+}
+int main(){
+    int n,W;
+    cin>>n>>W;
+    vector<Item>items(n);
+    for(int i=0;i<n;i++){
+        cin>>items[i].value;
+        cin>>items[i].weight;
+    }
+    double maxValue=fractionalKnapsack(items,W);
+    cout<<maxValue<<endl;
+    return 0;
+}

4.0_1Knapsack.cpp

@@ -0,0 +1,54 @@
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+int func(int i,int j,vector<int> &val,vector<int> &wt,vector<vector<int>> &dp){
+    if(i==0){
+        if(wt[i]<=j)return val[i];
+        else return 0;
+    }
+    if(dp[i][j]!=-1)return dp[i][j];
+    int notTake=func(i-1,j,val,wt,dp);
+    int take=0;
+    if(wt[i]<=j){
+        take=val[i]+func(i-1,j-wt[i],val,wt,dp);
+    }
+    return dp[i][j]=max(take,notTake);
+}
+int knapsack(int n,vector<int>&val,vector<int>&wt,int W){
+    vector<vector<int>>dp(n,vector<int>(W+1,-1));
+    int ans=func(n-1,W,val,wt,dp);   
+
+    return ans;
+}
+
+// int knapsack(int n,vector<int>&val,vector<int>&wt,int W){
+// iterative approach
+// can be space optimized
+//     vector<vector<int>>dp(n,vector<int>(W+1,0));
+//     for(int j=wt[0];j<=W;j++)dp[0][j]=val[0];
+//     for(int i=1;i<n;i++){
+//         for(int j=0;j<=W;j++){
+//             int notTake=dp[i-1][j];
+//             int take=0;
+//             if(wt[i]<=j){
+//                 take=val[i]+dp[i-1][j-wt[i]];
+//             }
+//             dp[i][j]=max(take,notTake);
+//         }
+//     }
+//     return dp[n-1][W];
+// }
+int main(){
+    int n,W;
+    cin>>n>>W;
+    vector<int>val(n),wt(n);
+    for(int i=0;i<n;i++){
+        cin>>val[i];
+    }
+    for(int i=0;i<n;i++){
+        cin>>wt[i];
+    }
+    int maxValue=knapsack(n,val,wt,W);
+    cout<<maxValue<<endl;
+    return 0;
+}

5.nQueenProblem.cpp

@@ -0,0 +1,56 @@
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+bool isValid(int row,int col,vector<vector<char>>&board,int n){
+
+    int dup_row=row;
+    int dup_col=col;
+    while(col>=0 && row>=0){
+        if(board[row][col]=='Q')return false;
+        row--;
+        col--;
+    }
+    row=dup_row;
+    col=dup_col;
+    while(col>=0){
+        if(board[row][col]=='Q')return false;
+        col--;
+    }
+    col=dup_col;
+    while(row<n && col>=0){
+        if(board[row][col]=='Q')return false;
+        row++;
+        col--;
+    }
+    return true;
+}
+bool placeQueen(int col,vector<vector<char>>&board,int n){
+    if(col==n)return true;
+    for(int i=0;i<n;i++){
+        if(isValid(i,col,board,n)){
+            board[i][col]='Q';
+            bool check=placeQueen(col+1,board,n);
+            if(check==true)return true;
+            board[i][col]='.';
+        }
+    }
+    return false;
+}
+int main(){
+    int n;
+    cin>>n;
+    vector<vector<char>>board(n,vector<char>(n));
+    for(int i=0;i<n;i++){
+        for(int j=0;j<n;j++){
+            board[i][j]='.';
+        }
+    }
+    placeQueen(0,board,n);
+    for(int i=0;i<n;i++){
+        for(int j=0;j<n;j++){
+            cout<<board[i][j]<<" ";
+        }
+        cout<<endl;
+    }
+    return 0;
+}