feat: update leetcode solutions: No.0724. Find Pivot Index

Author: yanglbme

solution/0700-0799/0724.Find Pivot Index/README.md

@@ -49,15 +49,39 @@ nums = [1, 2, 3]
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def pivotIndex(self, nums: List[int]) -> int:
+        sums = sum(nums)
+        pre_sum = 0
+        for i, v in enumerate(nums):
+            if (pre_sum << 1) == sums - v:
+                return i
+            pre_sum += v
+        return -1
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class Solution {
+    public int pivotIndex(int[] nums) {
+        int sums = 0;
+        for (int e : nums) {
+            sums += e;
+        }
+        int preSum = 0;
+        for (int i = 0; i < nums.length; ++i) {
+            // preSum == sums - nums[i] - preSum
+            if (preSum << 1 == sums - nums[i]) {
+                return i;
+            }
+            preSum += nums[i];
+        }
+        return -1;
+    }
+}
 ```
 
 ### **...**

solution/0700-0799/0724.Find Pivot Index/README_EN.md

@@ -64,13 +64,37 @@ There is no index that satisfies the conditions in the problem statement.
 ### **Python3**
 
 ```python
-
+class Solution:
+    def pivotIndex(self, nums: List[int]) -> int:
+        sums = sum(nums)
+        pre_sum = 0
+        for i, v in enumerate(nums):
+            if (pre_sum << 1) == sums - v:
+                return i
+            pre_sum += v
+        return -1
 ```
 
 ### **Java**
 
 ```java
-
+class Solution {
+    public int pivotIndex(int[] nums) {
+        int sums = 0;
+        for (int e : nums) {
+            sums += e;
+        }
+        int preSum = 0;
+        for (int i = 0; i < nums.length; ++i) {
+            // preSum == sums - nums[i] - preSum
+            if (preSum << 1 == sums - nums[i]) {
+                return i;
+            }
+            preSum += nums[i];
+        }
+        return -1;
+    }
+}
 ```
 
 ### **...**

solution/0700-0799/0724.Find Pivot Index/Solution.java

@@ -1,13 +1,17 @@
 class Solution {
     public int pivotIndex(int[] nums) {
-        int sum = Arrays.stream(nums).sum();
-        int s = 0;
+        int sums = 0;
+        for (int e : nums) {
+            sums += e;
+        }
+        int preSum = 0;
         for (int i = 0; i < nums.length; ++i) {
-            if (s << 1 == sum - nums[i]) {
+            // preSum == sums - nums[i] - preSum
+            if (preSum << 1 == sums - nums[i]) {
                 return i;
             }
-            s += nums[i];
+            preSum += nums[i];
         }
         return -1;
     }
-}
+}

solution/0700-0799/0724.Find Pivot Index/Solution.py

@@ -0,0 +1,9 @@
+class Solution:
+    def pivotIndex(self, nums: List[int]) -> int:
+        sums = sum(nums)
+        pre_sum = 0
+        for i, v in enumerate(nums):
+            if (pre_sum << 1) == sums - v:
+                return i
+            pre_sum += v
+        return -1