Add 673_Number_of_Longest_Increasing_Subsequence.java

Author: Sean Prashad

Dynamic Programming/673_Number_of_Longest_Increasing_Subsequence.java

@@ -0,0 +1,35 @@
+class Solution {
+    public int findNumberOfLIS(int[] nums) {
+        if (nums == null || nums.length == 0) {
+            return 0;
+        }
+
+        int[] dp = new int[nums.length], cnt = new int[nums.length];
+        Arrays.fill(dp, 1);
+        Arrays.fill(cnt, 1);
+
+        int result = 0, max = 1;
+
+        for (int i = 0; i < nums.length; i++) {
+            for (int j = 0; j < i; j++) {
+                if (nums[j] < nums[i]) {
+                    if (dp[j] + 1 == dp[i]) {
+                        cnt[i] += cnt[j];
+                    } else if (dp[j] + 1 > dp[i]) {
+                        dp[i] = dp[j] + 1;
+                        cnt[i] = cnt[j];
+                    }
+                }
+            }
+
+            if (dp[i] == max) {
+                result += cnt[i];
+            } else if (dp[i] > max) {
+                max = dp[i];
+                result = cnt[i];
+            }
+        }
+
+        return result;
+    }
+}