Merge pull request chipbk10#105 from chipbk10/TwoPointers

Solve Problem 844 - Backspace String Compare

Author: chipbk10

src/twopointers/Problem844_BackspaceStringCompare.java

@@ -0,0 +1,25 @@
+package twopointers;
+
+public class Problem844_BackspaceStringCompare {
+
+    private int down(String s, int i) {
+        int count = 0;
+        while (i >= 0 && (s.charAt(i) == '#' || count > 0)) {
+            count = (s.charAt(i--) == '#') ? count+1 : count-1;
+        }
+        return i;
+    }
+
+    public boolean backspaceCompare(String S, String T) {
+        for (int i = S.length()-1, j = T.length()-1; i >= 0 || j >= 0; i--, j--) {
+            i = down(S, i);
+            char cs = (i >= 0) ? S.charAt(i) : '.';
+
+            j = down(T, j);
+            char ct = (j >= 0) ? T.charAt(j) : '.';
+
+            if (cs != ct) return false;
+        }
+        return true;
+    }
+}