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In this tutorial, we will, as the title suggests, see how to append to a file in and SD Card connected to Arduino. Actually, it is quite simple. If you have gone through any previous articles on SD Card, then you only need to know thatmyFile = SD.open("example.txt", FILE_WRITE);opens example.txt in the append mode only. Thereafter, myFile.println(dataString);appends to the existing file, and doesn’t overwrite the existing content.If you haven’t gone through any other articles on SD Card, I’d suggest reading the "Store a new file in SD Card connected to Arduino" article. That is a detailed article containing the circuit ... Read More
In this tutorial, we will connect our Arduino Uno to an SD Card and extract the card info.Circuit DiagramThe circuit diagram is shown below −As you can see, you need to make the following connections −SD Card HolderArduino UnoVcc5VGNDGNDMISO12MOSI11SCK13CS10Only for the Vcc, make sure that your SD Card Holder takes 5V as input. If it takes in 3.3V, connect it to the 3.3V pin on Arduino Uno.Code WalkthroughWe will be walking through the example code that comes in with the inbuilt SD library. You can access it from File → Examples → SD → CardInfoWe begin with the inclusion of ... Read More
Suppose we have two strings s and t, we have to check whether s can be converted to t in k moves or less. In ith move you can do these operations.Select any index j (starting from 1) in s, such that 1
Suppose we have two positive values n and k, now we can make a binary string S_n by using following rules −S_1 = 0S_i = S_i-1 concatenate "1" concatenate reverse(invert(S_i-1)) for i > 1Here reverse(x) returns the reversed string x, and invert(x) flips all the bits in x.These are the example of four such stringsS_1 = "0"S_2 = "011"S_3 = "0111001"S_4 = "011100110110001"We have to find kth bit in S_n.So, if the input is like n = 4 k = 10, then the output will be 1 because S_4 = "011100110110001", so 10th bit is 1 (first bit is at ... Read More
Suppose we have an array nums and another value called target. Now we have to find the maximum number of non-empty non-overlapping subarrays such that the sum of values in each different subarray is same as target.So, if the input is like nums = [3, 2, 4, 5, 2, 1, 5] target = 6, then the output will be 2 as there are two subarrays [2, 4] and [1, 5] whose sum is same as 6.To solve this, we will follow these steps −t := a new set with single element 0temp := 0ans:= 0for each i in nums, dotemp ... Read More
Suppose we have a value n, consider an array nums with n elements, where arr[i] = (2*i)+1 for all i. Now in one operation, we can choose two indices x and y where 0 =0, doans:= ans + (n-j)q := q - 1j := j + 2return ansLet us see the following implementation to get better understanding −Example Live Demodef solve(n): ans=0 if n==1: return ans q=(n//2)-1 j=1 while q>=0: ans=ans+(n-j) q-=1 j+=2 return ans n = 4 print(solve(n))Input4Output4
Suppose we have a directed acyclic graph, with n vertices and nodes are numbered from 0 to n-1, the graph is represented by an edge list, where edges[i] = (u, v) represents a directed edge from node u to node v. We have to find the smallest set of vertices from which all nodes in the graph are reachable. (We can return the vertices in any order).So, if the input is likethen the output will be [0, 2, 3] because these two vertices are not reachable from any other vertices, so if we start from them we can cover all.To ... Read More
Suppose we have following function definition:def modify(arr, op, index): if op == 0: arr[index] += 1 if op == 1: for i in range(len(arr)): arr[i] *=2We have to find minimum number of function calls required to make a given array nums from one zero array of same size?So, if the input is like nums = [1, 5, 3], then the output will be 7 because, initially all elements are 0, [0, 0, 0]At first step increase second element by 1, so array is [0, 1, 0]Double second element ... Read More
Suppose we have an array arr this is holding a permutation of numbers from 1 to n. If we have a binary string of size n and initially all its bits set to zero. Now at each step i (Indexing starts from 1 for both the binary string and arr) from 1 to n, the bit at position arr[i] is set to 1. We also have another value m, and we need to find the latest step at which there exists a group of ones of size m. Here a group of ones means a contiguous substring of 1s such ... Read More
Suppose, we are provided a binary tree. We are also given a pointer to a node (named ‘u’) and we have to find the node situated just right of the provided node. The node situated to the given node's right must stay at the same level and the given node can either be a leaf node or an internal node.So, if the input is likeand u = 6, then the output will be 8.The node situated at the right of node 6 is node 8, so the value 8 is returned to us.To solve this, we will follow these steps ... Read More