add insertion sort

Author: havaevau

assets/img/insertion-sort.gif

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+# Insertion sort
+
+<div align="center">
+  <img src="https://github.com/iamlorddop/sorting-methods/blob/main/assets/img/insertion-sort.gif" alt="insertion-sort.gif">
+</div>

insertion-sort/README.md

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+let firstArray = [];
+let secondArray = [1, 1, 19, 4, 5];
+let thirdArray = [-1, 2, 4, -5, 10];
+let fourthArray = [-1, -5, -12, -2, 0];
+
+// Generate an array with random numbers
+for(let i = 0; i < 5; i++) {
+	firstArray.push(Math.round(Math.random() * 100));
+}
+
+console.log(`Before sort 1 array: ${firstArray}\nBefore sort 2 array: ${secondArray}\nBefore sort 3 array: ${thirdArray}\nBefore sort 4 array: ${fourthArray}`);
+
+function insertionSort(arr) { 
+   let key, j; 
+   for (let i = 1; i < arr.length; i++) { 
+      key = arr[i]; 
+      j = i - 1; 
+      /* Move elements of arr[0..i-1], that are 
+      greater than key, to one position ahead 
+      of their current position */
+      while (j >= 0 && arr[j] > key) { 
+         arr[j + 1] = arr[j]; 
+         j = j - 1; 
+      } 
+      arr[j + 1] = key; 
+   } 
+	return arr;
+} 
+
+insertionSort(firstArray);
+insertionSort(secondArray);
+insertionSort(thirdArray);
+insertionSort(fourthArray);
+
+console.log(`After sort 1 array: ${firstArray}\nAfter sort 2 array: ${secondArray}\nAfter sort 3 array: ${thirdArray}\nAfter sort 4 array: ${fourthArray}`);