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You can sort a list of dictionaries by values of the dictionary using the sorted function and passing it a lambda that tells which key to use for sorting. For example, A = [{'name':'john', 'age':45}, {'name':'andi', 'age':23}, {'name':'john', 'age':22}, {'name':'paul', 'age':35}, {'name':'john', 'age':21}] new_A = sorted(A, key=lambda x: x['age']) print(new_A)This will give the output:[{'name': 'john', 'age': 21}, {'name': 'john', 'age': 22}, {'name': 'andi', 'age': 23}, {'name': 'paul', 'age': 35}, {'name': 'john', 'age': 45}]You can also sort it in place using the sort function instead of the sorted function. For example, A ... Read More
If you have a dictionary of the following format:{ 'KEY1':{'name':'foo', 'data':1351, 'completed':100}, 'KEY2':{'name':'bar', 'data':1541, 'completed':12}, 'KEY3':{'name':'baz', 'data':58413, 'completed':18} }And you want to sort by the key, completed within each entry, in a ascending order, you can use the sorted function with a lambda that specifies which key to use to sort the data. For example, my_collection = { 'KEY1':{'name':'foo', 'data':1351, 'completed':100}, 'KEY2':{'name':'bar', 'data':1541, 'completed':12}, 'KEY3':{'name':'baz', 'data':58413, 'completed':18} } sorted_keys = sorted(my_collection, key=lambda x: (my_collection[x]['completed'])) print(sorted_keys)This will give the output:['KEY2', 'KEY3', 'KEY1']Read More
This algorithm will take an array and shuffle the contents of the array. It will generate a random permutation of the array elements.To solve this problem, we will swap elements starting from the last index to randomly generated an index in the array.Input and OutputInput: An array of integers: {1, 2, 3, 4, 5, 6, 7, 8} Output: Shuffle of array contents: 3 4 7 2 6 1 5 8 (Output may differ for next run)AlgorithmrandomArr(array, n)Input: The array, number of elements.Output: Shuffle the contents of the array.Begin for i := n – 1 down to 1, do ... Read More
The magic square is a square matrix, whose order is odd and where the sum of the elements for each row or each column or each diagonal is same. The sum of each row or each column or each diagonal can be found using this formula. n(n2+ 1)/2Here are the rules to construct a magic square −We will start from the middle column of the first row, of the matrix, and always go to the top left corner to place next numberIf the row exceeds, or the row is not in the matrix, then, change the column as left column and ... Read More
This algorithm is used to print the array elements in a spiral way. At first starting from the first row, print the whole content and then follow the last column to print, then the last row and so on, thus it prints the elements in spiral fashion. The time complexity of this algorithm is O(MN), M is the number of rows and N is the number of columns.Input and OutputInput: The matrix: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Output: Contents of ... Read More
Space ComplexitySpace complexity is an amount of memory used by the algorithm (including the input values of the algorithm), to execute it completely and produce the result.We know that to execute an algorithm it must be loaded in the main memory. The memory can be used in different forms:Variables (This includes the constant values and temporary values)Program InstructionExecutionAuxiliary SpaceAuxiliary space is extra space or temporary space used by the algorithms during its execution.Memory Usage during program executionInstruction Space is used to save compiled instruction in the memory.Environmental Stack is used to storing the addresses while a module calls another module ... Read More
Polynomial Time Approximation schemeWe can find some polynomial time solution for NP-Complete problems like 0-1 Knapsack problem or Subset sum problem. These problems are very popular in the real world, so there must be some ways to handle these problems.The Polynomial Time Approximation Scheme (PTAS) is a type to approximate algorithms for optimization problems. For the 0-1 Knapsack problem, there is a Pseudo Polynomial Solution, but when the values are large, the solution is not feasible. Then we need a PTAS solution.Some NP-complete problems like Graph Coloring, K-Center problem etc. they have no known polynomial time solution. PTAS used to approximate ... Read More
Amortize AnalysisThis analysis is used when the occasional operation is very slow, but most of the operations which are executing very frequently are faster. Data structures we need amortized analysis for Hash Tables, Disjoint Sets etc.In the Hash-table, the most of the time the searching time complexity is O(1), but sometimes it executes O(n) operations. When we want to search or insert an element in a hash table for most of the cases it is constant time taking the task, but when a collision occurs, it needs O(n) times operations for collision resolution.Aggregate MethodThe aggregate method is used to find ... Read More
Let us consider a string is given, we know that the string is a sequence of characters. The Lexicographical rotation is the rotation of string, to convert characters in lexicographical order.The solution is simple, we simply concatenate the given string with itself, then in another array, all rotation of strings are stored. After that sort the array in ascending order, the lowest value is the final result.Input and OutputInput: The String “BCAAFAABCD” Output: Rotated String: “AABCDBCAAF”AlgorithmminStrRotation(str)Input − The given string.Output − Minimum string rotation required.Begin n := length of str define strArr to store all rotations tempStr := ... Read More
Jarvis March algorithm is used to detect the corner points of a convex hull from a given set of data points.Starting from a leftmost point of the data set, we keep the points in the convex hull by anti-clockwise rotation. From a current point, we can choose the next point by checking the orientations of those points from the current point. When the angle is largest, the point is chosen. After completing all points, when the next point is the start point, stop the algorithm.Input and OutputInput: Set of points: {(-7, 8), (-4, 6), (2, 6), (6, 4), (8, 6), ... Read More