3주차 과제

problem-1/problem-1.test.js

@@ -1,4 +1,23 @@
+const exchange = (array, a,b)=>  {
+  [array[b], array[a]] = [array[a], array[b]];
+};
+
+const less = (a,b) => a<b;
+
 const bubbleSort = (array) => {
+  const {length} = array;
+  let isAligned = false;
+
+  for (let i = 0; i< length; i++) {
+    for (let j = 0; j< (length -i -1); j++) {
+      if (less(array[j + 1], array[j])) {
+        exchange (array, j, j+1);
+        isAligned = false;
+      } 
+      else isAligned = true; // exchange하지 않았을 경우 정렬된 상태
+    }
+    if (isAligned) return array; // j를 한 바퀴 돌 동안 isAligned가 true면 정렬된 배열
+  }
 };
 
 test.each([

problem-2/problem-2.test.js

@@ -1,4 +1,26 @@
+const exchange = (list, a,b) => {
+  [list[b], list[a]] = [list[a], list[b]];
+};
+
+const less = (a, b) => a < b;
+
+const findMinIndex = (list, startIndex) => {
+  let min = startIndex;
+
+  for (let j = startIndex + 1; j < list.length; j++) {
+    if (less(list[j], list[min])) {
+      min = j;
+    }
+  }
+  return min;
+}
+
 const selectionSort = (array) => {
+  for (let i = 0; i < array.length - 1; i++) {
+    const minIndex = findMinIndex(array, i);
+
+    exchange(array, i, minIndex);
+  }
 };
 
 test.each([

problem-3/problem-3.test.js

@@ -1,6 +1,24 @@
+const exchange = (list, a,b) => {
+  [list[b], list[a]] = [list[a], list[b]];
+};
+
+const less = (a,b) => a < b;
+
 const insertionSort = (array) => {
+  const {length} = array;
+
+  for (let i = 1; i < length; i++) {
+    for (let j = i; j > 0; j--) {
+      if (less(array[j], array[j - 1])) {
+        exchange(array, j, j - 1);
+      } else {
+        break;
+      }
+    }
+  }
 };
 
+
 test.each([
   [[5, 4, 3, 2, 1]],
   [[1, 2, 3, 4, 5]],

problem-4/problem-4.test.js

@@ -1,4 +1,29 @@
+const exchange = (list, a,b) => {
+  [list[b], list[a]] = [list[a], list[b]];
+};
+
+const less = (a,b) => a < b;
+
 const shellSort = (array) => {
+  const { length } = array;
+
+  let h = 1;
+  while (h < (length / 3)) {
+    h = 3 * h + 1;
+  }
+
+  while (h >= 1) {
+    for (let i = h; i < length; i++) {
+      for (let j = i; j >= 0; j = j - h) {
+        if (less(array[j], array[j - h])) {
+          exchange(array, j, j - h);
+        } else {
+          break;
+        }
+      }
+    }
+    h = Math.floor(h / 3);
+  }
 };
 
 test.each([

problem-5/problem-5.test.js

@@ -1,6 +1,41 @@
-const mergeSort = (array) => {
+const less = (a, b) => a < b;
+
+const mergeSort = (list, start = 0, end = list.length - 1) => {
+  if (start >= end) {
+    return;
+  }
+  const mid = Math.floor((start + end) / 2);
+
+  mergeSort(list, start, mid);
+  mergeSort(list, mid + 1, end);
+  merge(list, start, mid, end);
 };
 
+const merge = (list, start, mid, end) => {
+  let left = start;
+  let right = mid + 1;
+
+  const temp = [...list];
+
+  for (let i = start; i <= end; i++) {
+    if (left > mid) {
+      list[i] = temp[right];
+      right++;
+    } else if (right > end) {
+      list[i] = temp[left];
+      left++;
+    } else if (less(temp[left], temp[right])) {
+      list[i] = temp[left];
+      left++;
+    } else {
+      list[i] = temp[right];
+      right++;
+    }
+  }
+}
+
+
+
 test.each([
   [[8, 7, 6, 5, 4, 3, 2, 1]],
   [[1, 2, 3, 4, 5, 6, 7, 8]],

problem-6/problem-6.test.js

@@ -1,4 +1,65 @@
+const exchange = (list, a, b) => {
+  [list[b], list[a]] = [list[a], list[b]];
+};
+
+const less = (a, b) => a < b;
+
+const shuffle = (array) => {
+  let randomIndex;
+
+  for (let i = array.length; i > 0; i--) {
+    randomIndex = Math.floor(Math.random() * i);
+    i--;
+
+    [array[i], array[randomIndex]] = [array[randomIndex], array[i]];
+  }
+};
+
+const partition = (array, lo, hi) => {
+  let left = lo + 1;
+  let right = hi;
+
+  const pivot = array[lo];
+
+  while(true) {
+    while (less(array[left], pivot)) {
+      if(left === hi) {
+        break;
+      }
+
+      left++;
+    }
+
+    while (less(pivot, array[right])) {
+      if (right === lo) {
+        break;
+      }
+      right--;
+    }
+
+    if (left >= right) {
+      break;
+    }
+    exchange(array, left, right);
+  }
+
+  exchange(array, lo, right);
+  return right;
+};
+
+const sort = (array, lo, hi) => {
+  if (lo >= hi) {
+    return;
+  }
+
+  const j = partition(array, lo, hi);
+  sort(array, lo, j - 1);
+  sort(array, j + 1, hi);
+};
+
 const quickSort = (array) => {
+  shuffle(array);
+  sort(array, 0, array.length - 1);
 };
 
 test.each([