update is bst post order

Author: xiaoningning

PuzzleCoding/src/IsBSTPostOrder.java

@@ -19,17 +19,17 @@ public static boolean isBstPostOrder(int[] a, int left, int right) {
         }
 
         int i = left;
-        for (; i <= right; i++) {
+        for (; i < right; i++) {
             if (a[i] > a[right])
                 break;
         }
-
-        for (int j = i; j <= right; j++) {
+        int j = i;
+        for (; j < right; j++) {
             if (a[j] < a[right])
                 return false;
         }
 
-        return isBstPostOrder(a, left, i - 1) && isBstPostOrder(a, i, right - 1);
+        return isBstPostOrder(a, left, i - 1) && isBstPostOrder(a, i, j-1);
 
     }
 }

StringOps/src/StringOps.java

@@ -36,7 +36,7 @@ public static void main(String[] args) {
         perm("", s4);
 
         System.out.println("perm1 s4: " + s4);
-        perm1(s4.toCharArray(), s4.length()-1);
+        perm1(s4.toCharArray(), s4.length());
 
         String s6 = "abcd";
         System.out.println("move s6: " + s6);
@@ -311,7 +311,7 @@ public static void perm1(char[] s, int n) {
             System.out.println(s);
             return;
         }
-        for (int i = 0; i <= n; i++) {
+        for (int i = 0; i < n; i++) {
             swap(s, i, n - 1);
             perm1(s, n - 1);
             swap(s, i, n - 1);