add: slice adv. ops. exercises

16-slices/exercises/26-print-daily-requests/main.go

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+package main
+
+// ---------------------------------------------------------
+// EXERCISE: Print daily requests
+//
+//  You've got a requests log for a system in a slice: `reqs`.
+//  The log contains the total requests counts per 8 hours.
+//
+//  The reqs slice is a single-dimensional slice but you need
+//  to group the daily into a slice named: `daily`.
+//
+//  Please follow the instructions inside the code to solve
+//  the exercise.
+//
+//
+// EXPECTED OUTPUT
+//
+//   Please run `solution/main.go` to see the expected
+//   output.
+//
+//   go run solution/main.go
+//
+// ---------------------------------------------------------
+
+func main() {
+	//
+	// #1: DAILY REQUESTS DATA
+	//
+	// . The system collects and groups the requests per 8 hours
+	//
+	// . So there are 3 requests totals per day
+	//
+	// . Your code should be robust enough to work with
+	//   insufficient data. For example, in the last day
+	//   there are only two request totals: 100 and 150.
+	//
+	//   So, don't forget to handle that edge case as well.
+	//
+	// . Uncomment the code below and start
+	//
+
+	// reqs := []int{
+	// 	500, 600, 250,
+	// 	200, 400, 50,
+	// 	900, 800, 600,
+	// 	750, 250, 100,
+	// 	100, 150,
+	// }
+
+	//
+	// #2: Group the `reqs` per day into a slice named: `daily`
+	//
+	// . Create the daily slice using the `make` function
+	//
+	// . Anticipate the length argument to the make function using this data:
+	//
+	//   + The length of the reqs slice
+	//   + There are 3 requests totals per day
+	//   + There are residual elements (the last day)
+	//
+	//   ! So, do not blindly allocate a slice.
+	//
+	//   ! Allocate the slice efficiently with the exact size needed.
+	//
+	// . Then append to it the daily requests in a "loop"
+	//
+
+	//
+	// #3: Print the header:
+	//
+	// Day       Requests
+	// ====================
+	//
+
+	//
+	// #4: Print the data per day along with the totals:
+	//
+	// 1         500
+	// 1         600
+	// 1         250
+	// --------------------
+	//           1350  --> Print the daily total requests
+	//
+	// 2         200
+	// 2         400
+	// 2         50
+	// --------------------
+	//           650
+	//
+	//           2000  --> Also print the grand total
+
+	// ------------------------------------------------------------------------
+	//
+	// ❤️ NOTE ❤️
+	//
+	// If you could't solve this challenge. Please do not get discouraged.
+	//
+	// Look at the solution, then try to solve it again. This is valuable too.
+	//
+	// Then ️change the request data, the number of requests per day (now it's 3), etc
+	// and then try to solve it again.
+	//
+	// ------------------------------------------------------------------------
+}

16-slices/exercises/26-print-daily-requests/solution/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+func main() {
+	//
+	// DAILY REQUESTS DATA
+	//
+	reqs := []int{
+		500, 600, 250,
+		200, 400, 50,
+		900, 800, 600,
+		750, 250, 100,
+		100, 150,
+	}
+
+	//
+	// There are 3 requests per day
+	//
+	const N = 3
+
+	//
+	// Allocate the slice efficiently with the exact size needed
+	//
+	l := len(reqs)
+	size := l / N
+	if l%N != 0 {
+		size++
+	}
+	daily := make([][]int, 0, size)
+
+	//
+	// Group the `reqs` per day into a slice named: `daily`
+	//
+	for N < len(reqs) {
+		daily = append(daily, reqs[:N]) // add the current batch of nums to the `groups`
+		reqs = reqs[N:]                 // move the slice pointer for the next batch
+	}
+
+	//
+	// Add the residual elements to the group (len(reqs) % N)
+	//
+	daily = append(daily, reqs)
+
+	//
+	// Print the header:
+	//
+	fmt.Printf("%-10s%-10s\n", "Day", "Requests")
+	fmt.Println(strings.Repeat("=", 20))
+
+	//
+	// Print the data per day along with the totals:
+	//
+	var grand int
+
+	for i, d := range daily {
+		var sum int
+
+		for _, q := range d {
+			sum += q
+			fmt.Printf("%-10d%-10d\n", i+1, q)
+		}
+
+		fmt.Println(strings.Repeat("-", 20))
+		fmt.Printf("%10s%-10d\n\n", "", sum)
+
+		grand += sum
+	}
+
+	fmt.Printf("%10s%-10d\n", "", grand)
+}