Added task 1781.

Author: javadev

src/main/java/g1701_1800/s1781_sum_of_beauty_of_all_substrings/Solution.java

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+package g1701_1800.s1781_sum_of_beauty_of_all_substrings;
+
+// #Medium #String #Hash_Table #Counting #2022_04_27_Time_38_ms_(100.00%)_Space_51.4_MB_(22.14%)
+
+public class Solution {
+ public int beautySum(String s) {
+ int beauty = 0;
+ for (int i = 0; i < s.length(); i++) {
+ int[] numCountOfFreq = new int[s.length() + 1 - i];
+ int[] charFreq = new int[26];
+ charFreq[s.charAt(i) - 'a'] = 1;
+ numCountOfFreq[1] = 1;
+ int min = 1;
+ int max = 1;
+ for (int j = i + 1; j < s.length(); j++) {
+ char c = s.charAt(j);
+ charFreq[c - 'a']++;
+ int freq = charFreq[c - 'a'];
+ numCountOfFreq[freq - 1]--;
+ numCountOfFreq[freq]++;
+ if (numCountOfFreq[min] == 0) {
+ min++;
+ }
+ if (min > freq) {
+ min = freq;
+ }
+ if (max < freq) {
+ max = freq;
+ }
+ beauty += max - min;
+ }
+ }
+ return beauty;
+ }
+}

src/main/java/g1701_1800/s1781_sum_of_beauty_of_all_substrings/readme.md

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+1781\. Sum of Beauty of All Substrings
+
+Medium
+
+The **beauty** of a string is the difference in frequencies between the most frequent and least frequent characters.
+
+* For example, the beauty of `"abaacc"` is `3 - 1 = 2`.
+
+Given a string `s`, return _the sum of **beauty** of all of its substrings._
+
+**Example 1:**
+
+**Input:** s = "aabcb"
+
+**Output:** 5
+
+**Explanation:** The substrings with non-zero beauty are ["aab","aabc","aabcb","abcb","bcb"], each with beauty equal to 1.
+
+**Example 2:**
+
+**Input:** s = "aabcbaa"
+
+**Output:** 17 
+
+**Constraints:**
+
+* `1 <= s.length <= 500`
+* `s` consists of only lowercase English letters.

src/test/java/g1701_1800/s1781_sum_of_beauty_of_all_substrings/SolutionTest.java

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+package g1701_1800.s1781_sum_of_beauty_of_all_substrings;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class SolutionTest {
+ @Test
+ void beautySum() {
+ assertThat(new Solution().beautySum("aabcb"), equalTo(5));
+ }
+
+ @Test
+ void beautySum2() {
+ assertThat(new Solution().beautySum("aabcbaa"), equalTo(17));
+ }
+}