Signed-off-by: yuduozhou <[email protected]>

Author: yuduozhou

InsertIntervals.java

@@ -15,10 +15,10 @@ public ArrayList<Interval> insert(ArrayList<Interval> intervals, Interval newInt
         boolean inserted = false;
         for (int i = 0; i < intervals.size(); i++){
             Interval i1 =intervals.get(i);
-            if (smaller(i1, newInterval)){
+            if (i1.end < newInterval.start)){
                 result.add(i1);
             }
-            else if (smaller(newInterval, i1)){
+            else if (newInterval.end < i1.start){
                 result.add(newInterval);
                 result.addAll(intervals.subList(i, intervals.size()));
                 inserted = true;
@@ -31,11 +31,7 @@ else if (smaller(newInterval, i1)){
         if (!inserted) result.add(newInterval);
         return result;
     }
-    
-    public boolean smaller(Interval i1, Interval i2){
-        return i1.end < i2.start;
-    }
-    
+
     public Interval merge(Interval i1, Interval i2){
         int start = (i1.start < i2.start) ? i1.start : i2.start;
         int end = (i1.end > i2.end) ? i1.end : i2.end;

IntegerToRoman.java

@@ -0,0 +1,34 @@
+public class Solution {
+    public String intToRoman(int num) {
+        // Start typing your Java solution below
+        // DO NOT write main() function
+        if (num == 0) return "";
+        HashMap<Integer, String> map = new HashMap<Integer, String>();
+        setup(map);
+        int[] dig = new int[]{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
+        String result = "";
+        for (int i = 0; i < dig.length; i++){
+            int pivot = dig[i];
+            while(num - pivot >= 0){
+                result += map.get(pivot);
+                num -= pivot;
+            }
+        }
+        return result;        
+    }
+    public void setup(HashMap<Integer, String> map) {
+		map.put(1, "I");
+		map.put(4, "IV");
+		map.put(5, "V");
+		map.put(9, "IX");
+		map.put(10, "X");
+		map.put(40, "XL");
+		map.put(50, "L");
+		map.put(90, "XC");
+		map.put(100, "C");
+		map.put(400, "CD");
+		map.put(500, "D");
+		map.put(900, "CM");
+		map.put(1000, "M");
+	}
+}

InterleavingStrings.java

@@ -0,0 +1,34 @@
+public class Solution {
+    public boolean isInterleave(String s1, String s2, String s3) {
+        // Start typing your Java solution below
+        // DO NOT write main() function
+        int l1 = s1.length();
+        int l2 = s2.length();
+        int l3 = s3.length();
+        if (l3 != l1 + l2){
+            return false;
+        }
+        if (s1.equals("") || s2.equals("")){
+            return s2.equals(s3) || s1.equals(s3);
+        }
+
+        if (s1.charAt(l1 - 1) == s3.charAt(l3 - 1)){
+            // s3.last == both s1.last and s2.last
+            if (s2.charAt(l2 - 1) == s3.charAt(l3 - 1)) {
+                return (isInterleave(s1.substring(0, l1 - 1), s2, s3.substring(0, l3 - 1)) ||
+                        isInterleave(s1, s2.substring(0, l2 - 1), s3.substring(0, l3 - 1)));
+            }
+            // s3.last == s1.last
+            else {
+                return isInterleave(s1.substring(0, l1 - 1), s2, s3.substring(0, l3 - 1));
+            }
+        }
+        // s3.last == s2.last
+        else if (s2.charAt(l2 - 1) == s3.charAt(l3 - 1)) {
+            return isInterleave(s1, s2.substring(0, l2 - 1), s3.substring(0, l3 - 1));
+        }
+        else {
+            return false;
+        }
+    }
+}

JumpGame1.java

@@ -0,0 +1,15 @@
+public class Solution {
+    public boolean canJump(int[] A) {
+        // Start typing your Java solution below
+        // DO NOT write main() function
+        if (A.length < 1) return false;
+        if (A.length == 1) return true;
+        int marker = A.length - 1;
+        for (int i = A.length - 2; i >=0; i--){
+            if(A[i] >= marker - i){
+                marker = i;
+            }
+        }
+        return marker == 0;
+    }
+}

JumpGame2.java

@@ -0,0 +1,26 @@
+public class Solution {
+    public int jump(int[] A) {
+        // Start typing your Java solution below
+        // DO NOT write main() function
+        if (A.length <= 1) return 0;
+        int len = A.length;
+        int steps = 0;
+        int marker = 0;
+        // This will lead us to one step from the end.
+        while (A[marker] < len - 1 - marker){
+            int maxRange = marker + A[marker];
+            int maxFrom = marker;
+            for (int j = 1; j <= A[marker]; j++){
+                if (j + marker >= len) break;
+                if (A[marker + j] + marker + j > maxRange){
+                    maxRange = A[marker + j] + marker + j;
+                    maxFrom = marker + j;
+                }
+            }
+            marker = maxFrom;
+            steps++;
+        }
+        // Jump the last step.
+        return steps + 1;
+    }
+}