fd

Author: dingjikerbo

leetcode/solution/src/RestoreIPAddresses.java

@@ -1,3 +1,5 @@
+import java.util.ArrayList;
+import java.util.Deque;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -7,31 +9,33 @@ public class RestoreIPAddresses {
      * 注意，0可以，但是00，01， 010这种是不允许的
      */
     public List<String> restoreIpAddresses(String s) {
-        List<String> list = new LinkedList<>();
-        dfs(s, list, 0, 0, "");
-        return list;
+        List<String> result = new ArrayList<>();
+        dfs(s, 0, new LinkedList<>(), result);
+        return new ArrayList<>(result);
     }
 
-    private void dfs(String s, List<String> list, int index, int count, String cur) {
-        if (index >= s.length()) {
-            if (count == 4) {
-                list.add(cur);
-            }
+    private void dfs(String s, int index, Deque<String> ips, List<String> result) {
+        if (ips.size() > 4) {
             return;
         }
-
-        if (count == 4) {
+        if (index >= s.length()) {
+            if (ips.size() == 4) {
+                result.add(String.join(".", ips));
+            }
             return;
         }
-
-        int[][] RANGES = {
-                {0, 0}, {0, 9}, {10, 99}, {100, 255}
-        };
         for (int i = 1; i <= 3 && index + i <= s.length(); i++) {
             String t = s.substring(index, index + i);
-            int n = Integer.parseInt(t);
-            if (n >= RANGES[i][0] && n <= RANGES[i][1]) {
-                dfs(s, list, index + i, count + 1, (cur.isEmpty() ? "" : cur + ".") + t);
+            int k = Integer.parseInt(t);
+            if (i == 3 && k > 255) {
+                break;
+            }
+            ips.offer(t);
+            dfs(s, index + i, ips, result);
+            ips.pollLast();
+
+            if (k == 0) {
+                break;
             }
         }
     }

leetcode/src/Main.java

@@ -3,74 +3,46 @@
 public class Main {
 
     public static class Solution {
-        public double[] calcEquation(String[][] equations, double[] values, String[][] queries) {
-            HashMap<String, HashMap<String, Double>> table = new HashMap<>();
-            for (int i = 0; i < equations.length; i++) {
-                add(table, equations[i], values[i]);
-            }
-            double[] result = new double[queries.length];
-            HashSet<String> visited = new HashSet<>();
-            for (int i = 0; i < queries.length; i++) {
-                visited.clear();
-                result[i] = calc(table, visited, queries[i][0], queries[i][1]);
-            }
-            return result;
+
+        public List<String> restoreIpAddresses(String s) {
+            List<String> result = new ArrayList<>();
+            dfs(s, 0, new LinkedList<>(), result);
+            return new ArrayList<>(result);
         }
 
-        private double calc(HashMap<String, HashMap<String, Double>> table, HashSet<String> visited, String a, String b) {
-            HashMap<String, Double> map = table.get(a);
-            if (map == null) {
-                return -1.0;
+        private void dfs(String s, int index, Deque<String> ips, List<String> result) {
+            if (ips.size() > 4) {
+                return;
             }
-            if (a.equals(b)) {
-                return 1.0;
+            if (index >= s.length()) {
+                if (ips.size() == 4) {
+                    result.add(String.join(".", ips));
+                }
+                return;
             }
-            for (Map.Entry<String, Double> entry : map.entrySet()) {
-                String key = entry.getKey();
-                Double value = entry.getValue();
-
-                if (visited.contains(key)) {
-                    continue;
+            for (int i = 1; i <= 3 && index + i <= s.length(); i++) {
+                String t = s.substring(index, index + i);
+                int k = Integer.parseInt(t);
+                if (i == 3 && k > 255) {
+                    break;
                 }
+                ips.offer(t);
+                dfs(s, index + i, ips, result);
+                ips.pollLast();
 
-                visited.add(key);
-
-                double t = calc(table, visited, key, b);
-                if (t != -1.0) {
-                    return value * t;
+                if (k == 0) {
+                    break;
                 }
-
-                visited.remove(key);
-            }
-            return -1.0;
-        }
-
-        private void add(HashMap<String, HashMap<String, Double>> table, String[] equation, double value) {
-            HashMap<String, Double> map0 = table.get(equation[0]);
-            HashMap<String, Double> map1 = table.get(equation[1]);
-            if (map0 == null) {
-                map0 = new HashMap<>();
-                table.put(equation[0], map0);
-            }
-            if (map1 == null) {
-                map1 = new HashMap<>();
-                table.put(equation[1], map1);
             }
-            map0.put(equation[1], value);
-            map1.put(equation[0], 1 / value);
         }
     }
 
 
     public static void main(String[] args) {
-        Solution s = new Solution();
-        double[] res = s.calcEquation(new String[][]{
-                {"a", "b"}, {"b", "c"}
-        }, new double[]{2.0, 3.0}, new String[][]{
-                {"a", "c"}, {"b", "a"}, {"a", "e"}, {"a", "a"}, {"x", "x"}
-        });
-        for (double v : res) {
-            System.out.println(v);
+        Solution solution = new Solution();
+        List<String> result = solution.restoreIpAddresses("111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111");
+        for (String s : result) {
+            System.out.println(s);
         }
     }
 }