modify code

Author: algorithmzuo

src/class44/Code02_InsertS2MakeMostAlphabeticalOrder.java

@@ -22,8 +22,10 @@ public static String right(String s1, String s2) {
 return ans;
 }
 
-// 正式方法
-public static String max(String s1, String s2) {
+// 正式方法 O(N+M) + O(M^2)
+// N : s1长度
+// M : s2长度
+public static String maxCombine(String s1, String s2) {
 if (s1 == null || s1.length() == 0) {
 return s2;
 }
@@ -58,13 +60,35 @@ public static String max(String s1, String s2) {
 int comp = N + 1;
 for (int i = 0; i < N; i++) {
 if (rank[i] < rank[comp]) {
-int best = whereSplit(s1, s2, i);
+int best = bestSplit(s1, s2, i);
 return s1.substring(0, best) + s2 + s1.substring(best);
 }
 }
 return s1 + s2;
 }
 
+public static int bestSplit(String s1, String s2, int first) {
+int N = s1.length();
+int M = s2.length();
+int end = N;
+for (int i = first, j = 0; i < N && j < M; i++, j++) {
+if (s1.charAt(i) < s2.charAt(j)) {
+end = i;
+break;
+}
+}
+String bestPrefix = s2;
+int bestSplit = first;
+for (int i = first + 1, j = M - 1; i <= end; i++, j--) {
+String curPrefix = s1.substring(first, i) + s2.substring(0, j);
+if (curPrefix.compareTo(bestPrefix) >= 0) {
+bestPrefix = curPrefix;
+bestSplit = i;
+}
+}
+return bestSplit;
+}
+
 public static class DC3 {
 
 public int[] sa;
@@ -186,20 +210,6 @@ private int[] rank() {
 
 }
 
-public static int whereSplit(String str1, String str2, int first) {
-int M = str2.length();
-String bestPrefix = str2;
-int bestSplit = first;
-for (int i = first + 1, j = M - 1; i <= Math.min(str1.length(), first + M); i++, j--) {
-String curPrefix = str1.substring(first, i) + str2.substring(0, j);
-if (curPrefix.compareTo(bestPrefix) >= 0) {
-bestPrefix = curPrefix;
-bestSplit = i;
-}
-}
-return bestSplit;
-}
-
 // for test
 public static String randomNumberString(int len, int range) {
 char[] str = new char[len];
@@ -221,7 +231,7 @@ public static void main(String[] args) {
 String s1 = randomNumberString(s1Len, range);
 String s2 = randomNumberString(s2Len, range);
 String ans1 = right(s1, s2);
-String ans2 = max(s1, s2);
+String ans2 = maxCombine(s1, s2);
 if (!ans1.equals(ans2)) {
 System.out.println("Oops!");
 System.out.println(s1);
@@ -236,11 +246,11 @@ public static void main(String[] args) {
 System.out.println("性能测试开始");
 
 int s1Len = 1000000;
-int s2Len = 50;
+int s2Len = 500;
 String s1 = randomNumberString(s1Len, range);
 String s2 = randomNumberString(s2Len, range);
 long start = System.currentTimeMillis();
-max(s1, s2);
+maxCombine(s1, s2);
 long end = System.currentTimeMillis();
 System.out.println("运行时间 : " + (end - start) + " ms");
 System.out.println("性能测试结束");