前缀和 添加Go语言代码

animation-simulation/前缀和/leetcode523连续的子数组和.md

@@ -101,3 +101,35 @@ public:
 };
 ```
 
+Go Code:
+
+```go
+func checkSubarraySum(nums []int, k int) bool {
+    m := map[int]int{}
+    // 由于前缀和%k可能为0，所以需要给出没有元素的时候，索引位置，即-1
+    m[0] = -1
+    sum := 0
+    for i, num := range nums {
+        sum += num
+        key := sum % k
+        /*
+        // 题目中告诉k >= 1
+        key := sum
+        if k != 0 {
+            key = sum % k
+        }
+        */
+        if v, ok := m[key]; ok {
+            if i - v >= 2 {
+                return true
+            }
+            // 避免更新最小索引
+            continue
+        }
+        // 保存的是最小的索引
+        m[key] = i
+    }
+    return false
+}
+```
+

animation-simulation/前缀和/leetcode560和为K的子数组.md

@@ -183,3 +183,24 @@ public:
 };
 ```
 
+Go Code:
+
+```GO
+func subarraySum(nums []int, k int) int {
+    m := map[int]int{}
+    // m存的是前缀和，没有元素的时候，和为0，且有1个子数组(空数组)满足条件，即m[0] = 1
+    m[0] = 1
+    sum := 0
+    cnt := 0
+    for _, num := range nums {
+        sum += num
+        if v, ok := m[sum - k]; ok {
+            cnt += v
+        }
+        // 更新满足前缀和的子数组数量
+        m[sum]++
+    }
+    return cnt
+}
+```
+

animation-simulation/前缀和/leetcode724寻找数组的中心索引.md

@@ -108,3 +108,23 @@ public:
 };
 ```
 
+Go Code:
+
+```go
+func pivotIndex(nums []int) int {
+    presum := 0
+    for _, num := range nums {
+        presum += num
+    }
+    var leftsum int
+    for i, num := range nums {
+        // 比较左半和右半是否相同
+        if presum - leftsum - num == leftsum {
+            return i
+        }
+        leftsum += num
+    }
+    return -1
+}
+```
+

animation-simulation/前缀和/leetcode974和可被K整除的子数组.md

@@ -132,3 +132,21 @@ public:
 };
 ```
 
+Go Code:
+
+```go
+func subarraysDivByK(nums []int, k int) int {
+    m := make(map[int]int)
+    cnt := 0
+    sum := 0
+    m[0] = 1
+    for _, num := range nums {
+        sum += num
+        key := (sum % k + k) % k
+        cnt += m[key]
+        m[key]++
+    }
+    return cnt
+}
+```
+