zig : upgrade codes && rust : add codes for chapter_searching and chapter_dynamic_programming. (#591)

* zig : update zig codes

* rust : add codes for linear_search and hashing_search

* rust : add codes for linear_search and hashing_search

* rust : add codes for chapter_dynamic_programming

codes/zig/chapter_array_and_linkedlist/array.zig

@@ -63,7 +63,7 @@ pub fn traverse(nums: []i32) void {
 // 在数组中查找指定元素
 pub fn find(nums: []i32, target: i32) i32 {
     for (nums, 0..) |num, i| {
-        if (num == target) return @intCast(i32, i);
+        if (num == target) return @intCast(i);
     }
     return -1;
 }