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e720aa2d24
* Sync recent changes to the revised Word. * Revised the preface chapter * Revised the introduction chapter * Revised the computation complexity chapter * Revised the chapter data structure * Revised the chapter array and linked list * Revised the chapter stack and queue * Revised the chapter hashing * Revised the chapter tree * Revised the chapter heap * Revised the chapter graph * Revised the chapter searching * Reivised the sorting chapter * Revised the divide and conquer chapter * Revised the chapter backtacking * Revised the DP chapter * Revised the greedy chapter * Revised the appendix chapter * Revised the preface chapter doubly * Revised the figures
58 lines
1.6 KiB
Zig
58 lines
1.6 KiB
Zig
// File: two_sum.zig
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// Created Time: 2023-01-07
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// Author: sjinzh (sjinzh@gmail.com)
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const std = @import("std");
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const inc = @import("include");
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// 方法一：暴力枚举
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pub fn twoSumBruteForce(nums: []i32, target: i32) ?[2]i32 {
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var size: usize = nums.len;
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var i: usize = 0;
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// 两层循环，时间复杂度为 O(n^2)
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while (i < size - 1) : (i += 1) {
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var j = i + 1;
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while (j < size) : (j += 1) {
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if (nums[i] + nums[j] == target) {
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return [_]i32{@intCast(i), @intCast(j)};
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}
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}
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}
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return null;
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}
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// 方法二：辅助哈希表
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pub fn twoSumHashTable(nums: []i32, target: i32) !?[2]i32 {
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var size: usize = nums.len;
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// 辅助哈希表，空间复杂度为 O(n)
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var dic = std.AutoHashMap(i32, i32).init(std.heap.page_allocator);
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defer dic.deinit();
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var i: usize = 0;
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// 单层循环，时间复杂度为 O(n)
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while (i < size) : (i += 1) {
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if (dic.contains(target - nums[i])) {
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return [_]i32{dic.get(target - nums[i]).?, @intCast(i)};
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}
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try dic.put(nums[i], @intCast(i));
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}
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return null;
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}
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pub fn main() !void {
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// ======= Test Case =======
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var nums = [_]i32{ 2, 7, 11, 15 };
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var target: i32 = 9;
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// ====== Driver Code ======
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// 方法一
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var res = twoSumBruteForce(&nums, target).?;
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std.debug.print("方法一 res = ", .{});
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inc.PrintUtil.printArray(i32, &res);
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// 方法二
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res = (try twoSumHashTable(&nums, target)).?;
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std.debug.print("\n方法二 res = ", .{});
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inc.PrintUtil.printArray(i32, &res);
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_ = try std.io.getStdIn().reader().readByte();
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}
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