115. Distinct Subsequences (java)

Author: bluesword12350

solution/0115.Distinct Subsequences/Solution.java

@@ -0,0 +1,17 @@
+class Solution {
+    public int numDistinct(String s, String t) {
+        int[][] hash = new int[256][t.length() + 1];
+        int[] cnt = new int[t.length() + 1];
+        cnt[0] = 1;
+        for (int i = 0; i < t.length();) {
+            char c = t.charAt(i);
+            hash[c][++hash[c][0]] = ++i;
+        }
+        for(char c : s.toCharArray()) {
+            for(int i = hash[c][0]; i > 0; i--) {
+                cnt[hash[c][i]] += cnt[hash[c][i] - 1];
+            }
+        }
+        return cnt[t.length()];
+    }
+}