diff --git a/solution/0700-0799/0726.Number of Atoms/README.md b/solution/0700-0799/0726.Number of Atoms/README.md
index d7d1da455232e..2315f6e95b8de 100644
--- a/solution/0700-0799/0726.Number of Atoms/README.md
+++ b/solution/0700-0799/0726.Number of Atoms/README.md
@@ -98,7 +98,49 @@ tags:
#### Java
```java
-
+class Solution {
+ public String countOfAtoms(String formula) {
+ Map<String, Integer> map = new HashMap<>();
+ int[] stack = new int[1000];
+ int top = 0, multiplier = 1, freq = 0;
+ char[] c = formula.toCharArray();
+ for (int i = c.length - 1; i >= 0; i--) {
+ if (c[i] >= 'a' && c[i] <= 'z') {
+ int end = i--;
+ while (i >= 0 && c[i] >= 'a' && c[i] <= 'z') i--;
+ String key = new String(c, i, end - i + 1);
+ map.put(key, map.getOrDefault(key, 0) + Math.max(freq, 1) * multiplier);
+ freq = 0;
+ } else if (c[i] >= 'A' && c[i] <= 'Z') {
+ String key = new String(c, i, 1);
+ map.put(key, map.getOrDefault(key, 0) + Math.max(freq, 1) * multiplier);
+ freq = 0;
+ } else if (c[i] >= '0' && c[i] <= '9') {
+ freq = c[i] - '0';
+ int p = 10;
+ while (i - 1 >= 0 && c[i - 1] >= '0' && c[i - 1] <= '9') {
+ freq += p * (c[--i] - '0');
+ p *= 10;
+ }
+ } else if (c[i] == ')') {
+ stack[top++] = multiplier;
+ multiplier *= Math.max(freq, 1);
+ freq = 0;
+ } else {
+ multiplier = stack[--top];
+ }
+ }
+ List<String> keys = new ArrayList<>(map.keySet());
+ Collections.sort(keys);
+ StringBuilder sb = new StringBuilder();
+ for (String key : keys) {
+ sb.append(key);
+ int f = map.get(key);
+ if (f > 1) sb.append(f);
+ }
+ return sb.toString();
+ }
+}
```
#### C++
diff --git a/solution/0700-0799/0726.Number of Atoms/README_EN.md b/solution/0700-0799/0726.Number of Atoms/README_EN.md
index 641c1face2c92..76917f0343ba2 100644
--- a/solution/0700-0799/0726.Number of Atoms/README_EN.md
+++ b/solution/0700-0799/0726.Number of Atoms/README_EN.md
@@ -98,7 +98,49 @@ tags:
#### Java
```java
-
+class Solution {
+ public String countOfAtoms(String formula) {
+ Map<String, Integer> map = new HashMap<>();
+ int[] stack = new int[1000];
+ int top = 0, multiplier = 1, freq = 0;
+ char[] c = formula.toCharArray();
+ for (int i = c.length - 1; i >= 0; i--) {
+ if (c[i] >= 'a' && c[i] <= 'z') {
+ int end = i--;
+ while (i >= 0 && c[i] >= 'a' && c[i] <= 'z') i--;
+ String key = new String(c, i, end - i + 1);
+ map.put(key, map.getOrDefault(key, 0) + Math.max(freq, 1) * multiplier);
+ freq = 0;
+ } else if (c[i] >= 'A' && c[i] <= 'Z') {
+ String key = new String(c, i, 1);
+ map.put(key, map.getOrDefault(key, 0) + Math.max(freq, 1) * multiplier);
+ freq = 0;
+ } else if (c[i] >= '0' && c[i] <= '9') {
+ freq = c[i] - '0';
+ int p = 10;
+ while (i - 1 >= 0 && c[i - 1] >= '0' && c[i - 1] <= '9') {
+ freq += p * (c[--i] - '0');
+ p *= 10;
+ }
+ } else if (c[i] == ')') {
+ stack[top++] = multiplier;
+ multiplier *= Math.max(freq, 1);
+ freq = 0;
+ } else {
+ multiplier = stack[--top];
+ }
+ }
+ List<String> keys = new ArrayList<>(map.keySet());
+ Collections.sort(keys);
+ StringBuilder sb = new StringBuilder();
+ for (String key : keys) {
+ sb.append(key);
+ int f = map.get(key);
+ if (f > 1) sb.append(f);
+ }
+ return sb.toString();
+ }
+}
```
#### C++
diff --git a/solution/0700-0799/0726.Number of Atoms/Solution.java b/solution/0700-0799/0726.Number of Atoms/Solution.java
new file mode 100644
index 0000000000000..4a2cabc65937b
--- /dev/null
+++ b/solution/0700-0799/0726.Number of Atoms/Solution.java
@@ -0,0 +1,43 @@
+class Solution {
+ public String countOfAtoms(String formula) {
+ Map<String, Integer> map = new HashMap<>();
+ int[] stack = new int[1000];
+ int top = 0, multiplier = 1, freq = 0;
+ char[] c = formula.toCharArray();
+ for (int i = c.length - 1; i >= 0; i--) {
+ if (c[i] >= 'a' && c[i] <= 'z') {
+ int end = i--;
+ while (i >= 0 && c[i] >= 'a' && c[i] <= 'z') i--;
+ String key = new String(c, i, end - i + 1);
+ map.put(key, map.getOrDefault(key, 0) + Math.max(freq, 1) * multiplier);
+ freq = 0;
+ } else if (c[i] >= 'A' && c[i] <= 'Z') {
+ String key = new String(c, i, 1);
+ map.put(key, map.getOrDefault(key, 0) + Math.max(freq, 1) * multiplier);
+ freq = 0;
+ } else if (c[i] >= '0' && c[i] <= '9') {
+ freq = c[i] - '0';
+ int p = 10;
+ while (i - 1 >= 0 && c[i - 1] >= '0' && c[i - 1] <= '9') {
+ freq += p * (c[--i] - '0');
+ p *= 10;
+ }
+ } else if (c[i] == ')') {
+ stack[top++] = multiplier;
+ multiplier *= Math.max(freq, 1);
+ freq = 0;
+ } else {
+ multiplier = stack[--top];
+ }
+ }
+ List<String> keys = new ArrayList<>(map.keySet());
+ Collections.sort(keys);
+ StringBuilder sb = new StringBuilder();
+ for (String key : keys) {
+ sb.append(key);
+ int f = map.get(key);
+ if (f > 1) sb.append(f);
+ }
+ return sb.toString();
+ }
+}