added sieve_of_eratosthenes

C/0-1_knapsack.c

@@ -0,0 +1,74 @@
+#include<stdio.h>
+
+int max(int a,int b)  // function to find the maximum value
+{
+    if(b>a)
+    return b;
+    return a;
+}
+
+int main()
+{
+    printf("Enter the size of array:\n");
+    int n; 
+    scanf("%d",&n);
+
+    int w[n+1];  //weight array
+    printf("Enter the weights of elements\n");
+    for(int i = 1; i <= n; i++)
+    {
+        scanf("%d",&w[i]);
+    }
+    int val[n+1]; // value array
+    printf("Enter the value of elements\n");
+    for(int i = 1; i <= n; i++)
+    {
+        scanf("%d",&val[i]);
+    }
+
+    int weight; // weight of knapsack
+    printf("Enter the weight of knapsack\n");
+    scanf("%d",&weight);
+
+    int dp[n+1][weight+1];
+    for(int i=0;i<=n;i++)
+    {
+        for(int j=0;j<=weight;j++)
+        {
+            if(i==0||j==0)
+            dp[i][j]=0;   // initializing dp array
+        }
+    }
+
+    for(int i=1;i<=n;i++)
+    {
+        for(int j=1;j<=weight;j++)
+        {
+            if(j>=w[i])
+            dp[i][j]=max(val[i]+dp[i-1][j-w[i]],dp[i-1][j]);
+            else
+            dp[i][j]=dp[i-1][j];
+        }
+    }
+    printf("%d",dp[n][weight]);  // printing max value
+
+    return 0;
+}
+/*
+ Input: size of array, weight of elements, value of elements, weight of knapsack
+
+ Output: Maximum value of knapsack
+
+ time complexity: O(n*wg), 
+    where n is number of elements and wg is weight of knapsack
+
+
+ Sample input:
+   4
+   [3, 2, 4, 1]
+   [100, 20, 60, 40]
+   5
+
+ Output: 140
+
+*/ 

C/README.md

@@ -28,3 +28,5 @@ Format: -[Program name](name of the file)
 [Tree Traversals](Tree_traversals.c)
 
 [Fibonacci_series](fibonacci_series_code.c)
+
+[0/1 Knapsack](0-1_knapsack.c)

CPP/README.md

@@ -72,3 +72,5 @@ Format: -[Program name](name of the file)
 [N-Queens Proplem](N-QueensProblem.cpp)
 
 [Topological Sorting](Topological_sorting.cpp)
+
+[sieve of eratosthenes](sieve_of_eratosthenes.cpp)

CPP/sieve_of_eratosthenes.cpp

@@ -0,0 +1,34 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+    cout << "Enter the number:" << endl;
+    int n;
+      cin >> n;
+      // marking prime number as zero and non-prime as 1.
+
+    int a[n+1] = {0}; // initially assuming all numbers to be prime
+    a[0] = 1, a[1] = 1;  
+
+    vector <int> primes;
+
+    for(long long i = 2; i <= n; i++)
+    {
+        if(a[i] == 0)
+        {   
+            for(long long j =i * i; j <= n;j += i)  // iterating over all the multiples.
+            a[j] = 1;     // marking non-prime number as 1
+        }
+    }
+
+    for(int i = 1; i <= n; i++)
+    {
+        if(a[i] == 0)
+        primes.push_back(i);   //pushing all the primes in the primes vector.
+    }
+
+    for(int i=0;i<primes.size();i++)
+       cout << primes[i] << " ";
+
+}