feat: add solutions to lc problem: No.0881. Boats to Save People

Author: yanglbme

solution/0800-0899/0881.Boats to Save People/README.md

@@ -46,22 +46,47 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+“排序 + 双指针”实现。
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def numRescueBoats(self, people: List[int], limit: int) -> int:
+        people.sort()
+        num, i, j = 0, 0, len(people) - 1
+        while i <= j:
+            if people[i] + people[j] <= limit:
+                i += 1
+            j -= 1
+            num += 1
+        return num
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class Solution {
+    public int numRescueBoats(int[] people, int limit) {
+        Arrays.sort(people);
+        int num = 0;
+        int i = 0, j = people.length - 1;
+        while (i <= j) {
+            if (people[i] + people[j] <= limit) {
+                ++i;
+            }
+            --j;
+            ++num;
+        }
+        return num;
+    }
+}
 ```
 
 ### **...**

solution/0800-0899/0881.Boats to Save People/README_EN.md

@@ -49,13 +49,36 @@
 ### **Python3**
 
 ```python
-
+class Solution:
+    def numRescueBoats(self, people: List[int], limit: int) -> int:
+        people.sort()
+        num, i, j = 0, 0, len(people) - 1
+        while i <= j:
+            if people[i] + people[j] <= limit:
+                i += 1
+            j -= 1
+            num += 1
+        return num
 ```
 
 ### **Java**
 
 ```java
-
+class Solution {
+    public int numRescueBoats(int[] people, int limit) {
+        Arrays.sort(people);
+        int num = 0;
+        int i = 0, j = people.length - 1;
+        while (i <= j) {
+            if (people[i] + people[j] <= limit) {
+                ++i;
+            }
+            --j;
+            ++num;
+        }
+        return num;
+    }
+}
 ```
 
 ### **...**

solution/0800-0899/0881.Boats to Save People/Solution.java

@@ -0,0 +1,15 @@
+class Solution {
+    public int numRescueBoats(int[] people, int limit) {
+        Arrays.sort(people);
+        int num = 0;
+        int i = 0, j = people.length - 1;
+        while (i <= j) {
+            if (people[i] + people[j] <= limit) {
+                ++i;
+            }
+            --j;
+            ++num;
+        }
+        return num;
+    }
+}

solution/0800-0899/0881.Boats to Save People/Solution.py

@@ -1,23 +1,10 @@
 class Solution:
-    def numRescueBoats(self, people, limit):
-        """
-        :type people: List[int]
-        :type limit: int
-        :rtype: int
-        """
+    def numRescueBoats(self, people: List[int], limit: int) -> int:
         people.sort()
-        left = 0
-        right = len(people) - 1
-        ans = 0
-        while left < right:
-            if people[left] + people[right] <= limit:
-                ans += 1
-                left += 1
-                right -= 1
-            else:
-                ans += 1
-                right -= 1
-        else:
-            if left == right:
-                ans += 1
-        return ans
+        num, i, j = 0, 0, len(people) - 1
+        while i <= j:
+            if people[i] + people[j] <= limit:
+                i += 1
+            j -= 1
+            num += 1
+        return num