feat: add rust solution to lc problem: No.1746 (doocs#1231)

Author: xzhseh

solution/1700-1799/1746.Maximum Subarray Sum After One Operation/README.md

@@ -116,6 +116,36 @@ public:
 };
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    #[allow(dead_code)]
+    pub fn max_sum_after_operation(nums: Vec<i32>) -> i32 {
+        // Here f[i] represents the value of max sub-array that ends with nums[i] with no substitution
+        let mut f = 0;
+        // g[i] represents the case with exact one substitution
+        let mut g = 0;
+        let mut ret = 1 << 31;
+
+        // Begin the actual dp process
+        for e in &nums {
+            // f[i] = MAX(f[i - 1], 0) + nums[i]
+            let new_f = std::cmp::max(f, 0) + *e;
+            // g[i] = MAX(MAX(f[i - 1], 0) + nums[i] * nums[i], g[i - 1] + nums[i])
+            let new_g = std::cmp::max(std::cmp::max(f, 0) + *e * *e, g + *e);
+            // Update f[i] & g[i]
+            f = new_f;
+            g = new_g;
+            // Since we start at 0, update answer after updating f[i] & g[i]
+            ret = std::cmp::max(ret, g);
+        }
+
+        ret
+    }
+}
+```
+
 ### **Go**
 
 ```go

solution/1700-1799/1746.Maximum Subarray Sum After One Operation/README_EN.md

@@ -89,6 +89,36 @@ public:
 };
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    #[allow(dead_code)]
+    pub fn max_sum_after_operation(nums: Vec<i32>) -> i32 {
+        // Here f[i] represents the value of max sub-array that ends with nums[i] with no substitution
+        let mut f = 0;
+        // g[i] represents the case with exact one substitution
+        let mut g = 0;
+        let mut ret = 1 << 31;
+
+        // Begin the actual dp process
+        for e in &nums {
+            // f[i] = MAX(f[i - 1], 0) + nums[i]
+            let new_f = std::cmp::max(f, 0) + *e;
+            // g[i] = MAX(MAX(f[i - 1], 0) + nums[i] * nums[i], g[i - 1] + nums[i])
+            let new_g = std::cmp::max(std::cmp::max(f, 0) + *e * *e, g + *e);
+            // Update f[i] & g[i]
+            f = new_f;
+            g = new_g;
+            // Since we start at 0, update answer after updating f[i] & g[i]
+            ret = std::cmp::max(ret, g);
+        }
+
+        ret
+    }
+}
+```
+
 ### **Go**
 
 ```go

solution/1700-1799/1746.Maximum Subarray Sum After One Operation/Solution.rs

@@ -0,0 +1,25 @@
+impl Solution {
+    #[allow(dead_code)]
+    pub fn max_sum_after_operation(nums: Vec<i32>) -> i32 {
+        // Here f[i] represents the value of max sub-array that ends with nums[i] with no substitution
+        let mut f = 0;
+        // g[i] represents the case with exact one substitution
+        let mut g = 0;
+        let mut ret = 1 << 31;
+
+        // Begin the actual dp process
+        for e in &nums {
+            // f[i] = MAX(f[i - 1], 0) + nums[i]
+            let new_f = std::cmp::max(f, 0) + *e;
+            // g[i] = MAX(MAX(f[i - 1], 0) + nums[i] * nums[i], g[i - 1] + nums[i])
+            let new_g = std::cmp::max(std::cmp::max(f, 0) + *e * *e, g + *e);
+            // Update f[i] & g[i]
+            f = new_f;
+            g = new_g;
+            // Since we start at 0, update answer after updating f[i] & g[i]
+            ret = std::cmp::max(ret, g);
+        }
+
+        ret
+    }
+}