Refactor the articles related to searching algorithm. Add the chapter of binary search. Add the section of searching algorithm revisited. (#464)

codes/zig/chapter_searching/leetcode_two_sum.zig

@@ -0,0 +1,56 @@
+// File: leetcode_two_sum.zig
+// Created Time: 2023-01-07
+// Author: sjinzh (sjinzh@gmail.com)
+
+const std = @import("std");
+const inc = @import("include");
+
+// 方法一：暴力枚举
+pub fn twoSumBruteForce(nums: []i32, target: i32) ?[2]i32 {
+    var size: usize = nums.len;
+    var i: usize = 0;
+    // 两层循环，时间复杂度 O(n^2)
+    while (i < size - 1) : (i += 1) {
+        var j = i + 1;
+        while (j < size) : (j += 1) {
+            if (nums[i] + nums[j] == target) {
+                return [_]i32{@intCast(i32, i), @intCast(i32, j)};
+            }
+        }
+    }
+    return null;
+}
+
+// 方法二：辅助哈希表
+pub fn twoSumHashTable(nums: []i32, target: i32) !?[2]i32 {
+    var size: usize = nums.len;
+    // 辅助哈希表，空间复杂度 O(n)
+    var dic = std.AutoHashMap(i32, i32).init(std.heap.page_allocator);
+    defer dic.deinit();
+    var i: usize = 0;
+    // 单层循环，时间复杂度 O(n)
+    while (i < size) : (i += 1) {
+        if (dic.contains(target - nums[i])) {
+            return [_]i32{dic.get(target - nums[i]).?, @intCast(i32, i)};
+        }
+        try dic.put(nums[i], @intCast(i32, i));
+    }
+    return null;
+}
+
+
+pub fn main() !void {
+    // ======= Test Case =======
+    var nums = [_]i32{ 2, 7, 11, 15 };
+    var target: i32 = 9;
+
+    // ====== Driver Code ======
+    // 方法一
+    var res = twoSumBruteForce(&nums, target).?;
+    std.debug.print("方法一 res = ", .{});
+    inc.PrintUtil.printArray(i32, &res); 
+    // 方法二
+    res = (try twoSumHashTable(&nums, target)).?;
+    std.debug.print("\n方法二 res = ", .{});
+    inc.PrintUtil.printArray(i32, &res); 
+}