add solution for two_sum

Author: grokcoder

Diff for: .gitignore

@@ -0,0 +1,28 @@
+# Created by .ignore support plugin (hsz.mobi)
+### Example user template template
+### Example user template
+
+# IntelliJ project files
+.idea
+*.iml
+out
+gen### Rust template
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+
+
+#Added by cargo
+#
+#already existing elements are commented out
+
+/target
+#**/*.rs.bk

Diff for: Cargo.toml

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+[package]
+name = "rust-leetcode"
+version = "0.1.0"
+authors = ["Xiaoyi Wang <[email protected]>"]
+edition = "2018"
+
+[dependencies]

Diff for: src/lc-001.rs

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+use std::collections::HashMap;
+
+impl Solution {
+
+    pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {
+
+        let mut rs: Vec<i32> = Vec::new();
+        for i in 0..nums.len() {
+            for j in i +1 .. nums.len() {
+                if nums[i] + nums[j] == target {
+                    rs.push(i as i32);
+                    rs.push(j as i32);
+                    return rs
+                }
+            }
+        }
+        return rs;
+    }
+
+    // the second solution
+    pub fn two_sum_s2(nums: Vec<i32>, target: i32) -> Vec<i32> {
+
+        let mut i1 :i32 = 0;
+        let mut i2 = 0;
+        let mut m: HashMap<i32, i32> = HashMap::new();
+
+        for i in 0.. nums.len() {
+            let sub = target - &nums[i];
+            if m.contains_key(&sub){
+                i1 = i as i32;
+                i2 = *m.get(&sub).unwrap();
+                break;
+            }else {
+                m.insert(nums[i], i as i32);
+            }
+        }
+
+        if i1 < i2 {
+            return vec![i1, i2];
+        }else {
+            return vec![i2, i1];
+        }
+    }
+}

Diff for: src/main.rs

@@ -0,0 +1,11 @@
+
+use std::fs::read;
+
+fn main() {
+    println!("Hello, world!");
+
+//    let tnums = vec![2, 3, 4, 5];
+//    let x = two_sum_s2(tnums, 5);
+//
+//    println!("the index is {:?}", x)
+}