hello-algo/codes/zig/chapter_computational_complexity/leetcode_two_sum.zig
2023-01-11 12:34:54 +08:00

61 lines
1.8 KiB
Zig

// File: leetcode_two_sum.zig
// Created Time: 2023-01-07
// Author: sjinzh (sjinzh@gmail.com)
const std = @import("std");
const inc = @import("include");
const SolutionBruteForce = struct {
pub fn twoSum(self: *SolutionBruteForce, nums: []i32, target: i32) [2]i32 {
_ = self;
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 undefined;
}
};
const SolutionHashMap = struct {
pub fn twoSum(self: *SolutionHashMap, nums: []i32, target: i32) ![2]i32 {
_ = self;
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 undefined;
}
};
// Driver Code
pub fn main() !void {
// ======= Test Case =======
var nums = [_]i32{ 2, 7, 11, 15 };
var target: i32 = 9;
// 方法一
var slt1 = SolutionBruteForce{};
var res = slt1.twoSum(&nums, target);
std.debug.print("方法一 res = ", .{});
inc.PrintUtil.printArray(i32, &res);
// 方法二
var slt2 = SolutionHashMap{};
res = try slt2.twoSum(&nums, target);
std.debug.print("方法二 res = ", .{});
inc.PrintUtil.printArray(i32, &res);
}