常用的數(shù)據(jù)交換方法有: 1. 輔助變量法; 2. 加法運(yùn)算法; 3. 異或運(yùn)算法;
下面進(jìn)行比較測(cè)試: - 主要比較耗時(shí) - 比較平臺(tái)為matlab
% 基本設(shè)置close allclearclca = 100; % 交換數(shù)據(jù)1b = 200; % 交換數(shù)據(jù)2c = 999999; % 交換次數(shù)% method 1a1 = a;b1 = b;tic;for i = 1 : c temp = a1; a1 = b1; b1 = temp;endtime_1 = toc;% method 2a2 = a;b2 = b;tic;for i = 1 : c a2 = a2 + b2; % 運(yùn)行此步驟后,a2 = a2(原始) + b2(原始) b2 = a2 - b2; % 運(yùn)行此步驟后,b2 = a2(原始) + b2(原始) - b2(原始) = a2(原始) a2 = a2 - b2; % 運(yùn)行此步驟后,a2 = a2(原始) + b2(原始) - (a2(原始) + b2(原始) - b2(原始)) = b2(原始)endtime_2 = toc;% method 3% 針對(duì)16bit數(shù)據(jù)% 利用異或運(yùn)算基本原理:a = a^b^b; a^b = b^aa3 = a;b3 = b;tic;for i = 1 : c a3 = bitxor(a3, b3, 'uint16'); % 運(yùn)行此步驟后,a3 = a3(原始) ^ b3(原始) b3 = bitxor(a3, b3, 'uint16'); % 運(yùn)行此步驟后,b3 = a3(原始) ^ b3(原始) ^ b3(原始) = a3(原始) a3 = bitxor(a3, b3, 'uint16'); % 運(yùn)行此步驟后,a3 = a3(原始) ^ b3(原始) ^ (a3(原始) ^ b3(原始) ^ b3(原始)) = b3(原始)endtime_3 = toc;比較結(jié)果:
bar([time_1, time_2, time_3])xlabel('方法'), ylabel('耗時(shí)(s)')新聞熱點(diǎn)
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