Modified question 35. Search Insert Position: 1. added notes, 2. shorten the variable name length.

Author: kflili

Algorithms Basics/Chapter 6. Binary Search/35. Search Insert Position.cs

@@ -1,20 +1,28 @@
+// keynote: 
+// 1. start from boundary checking
+// 2. use simple real case to determine the index in the end
 public class Solution {
     public int SearchInsert(int[] nums, int target) {
-        if (nums == null || nums.Length == 0) return 0;
-        int start = 0;
-        int end = nums.Length - 1;
-        while (start + 1 < end) {
-            int mid = start + (end - start) / 2;
-            if (nums[mid] == target) {
-                return mid;
-            } else if (nums[mid] < target) {
-                start = mid;
+        if (nums == null || nums.Length == 0) {
+            return 0;
+        }
+        int l = 0, r = nums.Length - 1, m;
+        while (l + 1 < r) {
+            m = l + (r - l) / 2;
+            if (nums[m] == target) {
+                return m;
+            } else if (nums[m] < target) {
+                l = m + 1;
             } else {
-                end = mid;
+                r = m - 1;
             }
         }
-        if (target <= nums[start]) return start;
-        if (nums[start] < target && target <= nums[end]) return end;
-        return end+1;
+        if (target <= nums[l]) {
+            return l;
+        }
+        if (target > nums[r]) {
+            return r + 1;
+        }
+        return r;
     }
 }