update

leetcode/MaximumSubarray.java

@@ -4,18 +4,21 @@
  * the contiguous subarray [4,−1,2,1] has the largest sum = 6.
  */ 
 public class MaximumSubarray {
+/********************** updated 2013/11/26 *********************/
     public int maxSubArray(int[] A) {
-        int max = A[0], sum = 0;
+        int max = Integer.MIN_VALUE, tempMax = 0;
         for(int i = 0; i < A.length; i++) {
-            sum += A[i];
-            max = Math.max(max, sum);
-            sum = sum < 0 ? 0 : sum;
+            tempMax += A[i];
+            if(max < tempMax) 
+                max = tempMax;
+            if(tempMax < 0)
+                tempMax = 0;
         }
         return max;
     }
 
-    /** Below is from wikipedia */
-/*  public int maxSubArray(int[] A) {
+/****************** Below is from wikipedia ******************/
+    public int maxSubArray(int[] A) {
         int max_so_far = A[0], max_ending_here = A[0];
         for(int i = 1; i < A.length; i++) {//recursion starts from 1.
             if(max_ending_here < 0)
@@ -26,5 +29,5 @@ public int maxSubArray(int[] A) {
                 max_so_far = max_ending_here;
         }
         return max_so_far;
-    }*/
+    }
 }

leetcode/PascalTriangleII.java

@@ -1,27 +1,41 @@
-package info.mitcc.leetcode;
+/*
+ * Given an index k, return the kth row of the Pascal's triangle.
 
-import java.util.ArrayList;
-import java.util.Scanner;
+ * For example, given k = 3,
+ * Return [1,3,3,1].
 
+ * Note:
+ * Could you optimize your algorithm to use only O(k) extra space? 
+ */
 public class PascalTriangleII {
-	public ArrayList<Integer> getRow(int rowIndex) {
-		if(rowIndex < 0)
-			throw new IllegalArgumentException();
-		ArrayList<Integer> list = new ArrayList<Integer>();
-		list.add(1);
-		if(rowIndex == 0)
-			return list;
-		else {
-			ArrayList<Integer> tempList = this.getRow(rowIndex - 1);
-			for(int i = 1; i < rowIndex; i++)
-				list.add(tempList.get(i - 1) + tempList.get(i));
-			list.add(1);
-			return list;
-		}
+/**************************** updated 2013/11/26 *********************/
+    public ArrayList<Integer> getRow(int rowIndex) {
+        ArrayList<Integer> res = new ArrayList<Integer>(), temp = new ArrayList<Integer>();
+        res.add(1);
+        temp.add(1);
+        temp.add(1);
+        for(int i = 1; i <= rowIndex; i++) {
+            res = new ArrayList<Integer>();
+            res.add(1);
+            for(int j = 0; j <= i - 2; j++) 
+                res.add(temp.get(j) + temp.get(j + 1));
+            res.add(1);
+            temp = res;
+        }
+        return res;
+    }
+
+/*********************************************************************/
+
+    public ArrayList<Integer> getRow(int rowIndex) {
+        ArrayList<Integer> res = new ArrayList<Integer>();
+        res.add(1);
+        if(rowIndex > 0) {
+            ArrayList<Integer> temp = getRow(rowIndex - 1);
+            for(int i = 0; i <= rowIndex - 2; i++) 
+                res.add(temp.get(i) + temp.get(i + 1));
+            res.add(1);
+        }
+        return res;
     }
-
-	public static void main(String[] args) {
-		Scanner in = new Scanner(System.in);
-		System.out.println(new PascalTriangleII().getRow(in.nextInt()));
-	}
 }