Update 416_Partition_Equal_Subset_Sum.java

Author: Sean Prashad

Dynamic Programming/416_Partition_Equal_Subset_Sum.java

@@ -1,31 +1,30 @@
 class Solution {
     public boolean canPartition(int[] nums) {
-        if (nums == null || nums.length == 0) {
-            return false;
-        }
-
-        int totalSum = 0;
+        int sum = 0;
         for (int num : nums) {
-            totalSum += num;
+            sum += num;
         }
-        if (totalSum % 2 == 1) {
+        if (sum % 2 != 0) {
             return false;
         }
-        totalSum /= 2;
 
-        boolean[][] dp = new boolean[nums.length + 1][totalSum + 1];
+        sum /= 2;
+
+        boolean[][] dp = new boolean[nums.length + 1][sum + 1];
         dp[0][0] = true;
 
         for (int i = 1; i <= nums.length; i++) {
-            for (int j = 1; j <= totalSum; j++) {
-                if (nums[i - 1] <= j) {
+            dp[i][0] = true;
+        }
+
+        for (int i = 1; i <= nums.length; i++) {
+            for (int j = 1; j <= sum; j++) {
+                if (j >= nums[i - 1]) {
                     dp[i][j] = dp[i - 1][j] || dp[i - 1][j - nums[i - 1]];
-                } else {
-                    dp[i][j] = dp[i - 1][j];
                 }
             }
         }
 
-        return dp[nums.length][totalSum];
+        return dp[nums.length][sum];
     }
 }