{"id":1528,"date":"2023-05-28T10:25:11","date_gmt":"2023-05-28T02:25:11","guid":{"rendered":"https:\/\/xinchewhd.com.cn\/?p=1528"},"modified":"2023-05-28T10:25:11","modified_gmt":"2023-05-28T02:25:11","slug":"%e3%80%90%e7%ae%97%e6%b3%95%e3%80%912-%e5%88%a4%e6%96%ad%e4%b8%80%e4%b8%aa%e6%95%b4%e6%95%b0%e6%98%af%e5%90%a6%e6%98%af-2-%e7%9a%84%e5%b9%82%e6%ac%a1%e6%96%b9","status":"publish","type":"post","link":"https:\/\/xinchewhd.com.cn\/index.php\/%e7%ae%97%e6%b3%95\/%e3%80%90%e7%ae%97%e6%b3%95%e3%80%912-%e5%88%a4%e6%96%ad%e4%b8%80%e4%b8%aa%e6%95%b4%e6%95%b0%e6%98%af%e5%90%a6%e6%98%af-2-%e7%9a%84%e5%b9%82%e6%ac%a1%e6%96%b9\/","title":{"rendered":"\u3010\u7b97\u6cd5\u30112. \u5224\u65ad\u4e00\u4e2a\u6574\u6570\u662f\u5426\u662f 2 \u7684\u5e42\u6b21\u65b9"},"content":{"rendered":"
\n

\u9898\u76ee<\/span><\/h2>\n
<\/figure>\n
\n
\n
\u7ed9\u4f60\u4e00\u4e2a\u6574\u6570 n\uff0c\u8bf7\u4f60\u5224\u65ad\u8be5\u6574\u6570\u662f\u5426\u662f 2 \u7684\u5e42\u6b21\u65b9\u3002\u5982\u679c\u662f\uff0c\u8fd4\u56de true \uff1b\u5426\u5219\uff0c\u8fd4\u56de false \u3002\u5982\u679c\u5b58\u5728\u4e00\u4e2a\u6574\u6570 x \u4f7f\u5f97 n== 2^x\uff0c\u5219\u8ba4\u4e3a n \u662f 2 \u7684\u5e42\u6b21\u65b9\u3002<\/section>\n<\/section>\n
https:\/\/leetcode.cn\/problems\/power-of-two\/description\/<\/section>\n<\/blockquote>\n

\u89e3\u9898\u601d\u8def<\/span><\/h2>\n
<\/figure>\n
\u5982\u679c\u4e00\u4e2a\u6570\u662f2\u7684\u5e42\u6b21\u65b9\uff0c\u90a3\u4e48\u8fd9\u4e2a\u6574\u6570\u80af\u5b9a\u6ee1\u8db3\u4e24\u4e2a\u6761\u4ef6\uff1a<\/span><\/section>\n
    \n
  1. \u5927\u4e8e0<\/span><\/li>\n
  2. \u4e8c\u8fdb\u5236\u8868\u8fbe\u4e2d\uff0c\u6709\u4e14\u53ea\u67091\u4e2a\u4f4d\u7f6e\u4e3a1\u3002<\/span><\/li>\n<\/ol>\n\n\n\n\n\n\n\n\n\n
    n<\/th>\n\u4e8c<\/span>\u8fdb<\/span>\u5236\u8868\u8fbe\u00a0<\/span><\/th>\n<\/tr>\n
    2^0 ==\u00a01<\/span><\/td>\n0000 0001<\/span><\/td>\n<\/tr>\n
    2^1 == 2<\/span><\/td>\n0000\u00a00010<\/span><\/td>\n<\/tr>\n
    2^2\u00a0== 4\u00a0<\/span><\/td>\n0000\u00a00100<\/span><\/td>\n<\/tr>\n
    2^3 == 8<\/span><\/td>\n0000\u00a01000<\/span><\/td>\n<\/tr>\n
    ...\u00a0<\/span><\/td>\n...\u00a0<\/span><\/td>\n<\/tr>\n
    2^n<\/span><\/td>\n\u7b2cn\u4f4d\u4e3a1\uff0c\u5176\u4ed6\u5747\u4e3a0\u3002n\u4ece0\u5f00\u59cb\u3002<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \u89e3\u6cd5\u4e00\uff1a\u83b7\u53d6\u4e8c\u8fdb\u5236\u6700\u4f4e\u4f4d<\/span><\/h2>\n
    <\/figure>\n

    \u6211\u4eec\u9996\u9009\u53ef\u4ee5\u6392\u9664 <\/span><=0<\/span> \u7684\u6574\u6570\uff0c\u7136\u540e\u53ef\u4ee5\u4f7f\u7528\u83b7\u53d6\u4e8c\u8fdb\u5236\u6700\u4f4e\u4f4d\u7684\u65b9\u5f0f\u53bb\u5224\u65ad <\/span>>0<\/span> \u7684\u6574\u6570\uff0c\u6211\u4eec\u77e5\u9053\u83b7\u53d6\u6700\u4f4e\u4f4d\u7684\u65b9\u6cd5\u662f\u00a0 <\/span>n & (-n)<\/span> \uff0c\u56e0\u4e3a\u8981\u6c42n\u53ea\u80fd\u5305\u542b\u4e00\u4e2a1\uff0c\u6240\u4ee5\u52bf\u5fc5 <\/span>n = n & (-n)<\/span>\u3002<\/span><\/p>\n\n\n\n\n\n\n\n\n\n
    n<\/th>\n-n<\/th>\nn & (-n)<\/th>\n<\/tr>\n
    0000 0001<\/span><\/td>\n1111 1111
    \n<\/span><\/td>\n    		0000 0001<\/span><\/td>\n<\/tr>\n
    0000 0010<\/span><\/td>\n1111 1110
    \n<\/span><\/td>\n    		0000 0010<\/span><\/td>\n<\/tr>\n
    0000 0100<\/span><\/td>\n1111 1100\u00a0<\/span><\/td>\n0000 0100<\/span><\/td>\n<\/tr>\n
    0000 1000<\/span><\/td>\n1111 1000\u00a0<\/span><\/td>\n0000\u00a01000<\/span><\/td>\n<\/tr>\n
    0001\u00a00000<\/span><\/td>\n1111 0000
    \n<\/span><\/td>\n    		0001\u00a00000<\/span><\/td>\n<\/tr>\n
    ......<\/span><\/td>\n....<\/span>.<\/span>.<\/span><\/td>\n....<\/span>.<\/span>.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    \n

    \u4ee3\u7801\u5b9e\u73b0<\/span><\/p>\n

    \n
    class<\/span> Solution<\/span> <\/span>{<\/span><\/code>\n    public<\/span> boolean<\/span> isPowerOfTwo<\/span>(int<\/span> n)<\/span> <\/span>{<\/span><\/code>\n        if<\/span>(n <= 0<\/span>){<\/span><\/code>\n            return<\/span> false<\/span>;<\/span><\/code>\n        }<\/span><\/code>\n        \/\/ \u53ea\u6709\u4e00\u4e2a\u4f4d\u4e3a1\uff0c\u6240\u6709lowbit \u5e94\u8be5\u7b49\u4e8en\u672c\u8eab<\/span><\/span><\/code>\n        return<\/span> (n & -n) == n;<\/span><\/code>\n    }<\/span><\/code>}<\/span><\/code><\/pre>\n<\/section>\n
    <\/section>\n
    \u590d\u6742\u5ea6\u5206\u6790<\/span><\/p>\n
    \u65f6\u95f4\u590d\u6742\u5ea6: O(1)\u3002<\/span><\/section>\n
    \u7a7a\u95f4\u590d\u6742\u5ea6: O(1)\u3002<\/span><\/section>\n
    \u00a0<\/span><\/section>\n
    \u89e3\u6cd5\u4e8c\uff1a\u5220\u9664\u6700\u4f4e\u4f4d<\/span><\/h2>\n
    <\/figure>\n
    \u89e3\u9898\u601d\u8def\u540c\u89e3\u6cd5\u4e00\uff0c\u7136\u540e\u6211\u4eec\u5c06\u83b7\u53d6\u6700\u4f4e\u4f4d\u6539\u4e3a\u5220\u9664\u6700\u4f4e\u4f4d\uff0c\u56e0\u4e3an\u7684\u4e8c\u8fdb\u5236\u8868\u793a\u4e2d\u6709\u4e14\u53ea\u67091\u4e2a1\uff0c\u90a3\u4e48\u5220\u6389\u6700\u540e\u4e00\u4e2a1\u4e4b\u540e\u5269\u4e0b\u7684\u5e94\u8be5\u90fd\u662f0\u624d\u5bf9\uff0c\u5373 <\/span>(n & (n - 1)) == 0<\/span>\u3002<\/span><\/p>\n\n\n\n\n\n\n\n\n\n
    n<\/th>\nn - 1<\/th>\nn & (n - 1)<\/th>\n<\/tr>\n
    0000 0001<\/span><\/td>\n0000 0000
    \n<\/span><\/td>\n    		0000 0000<\/span><\/td>\n<\/tr>\n
    0000 0010<\/span><\/td>\n0000 0001<\/span><\/span><\/td>\n0000 0000<\/span><\/span><\/td>\n<\/tr>\n
    0000 0100<\/span><\/td>\n00<\/span>00 0011<\/span><\/span><\/td>\n0000 0000<\/span><\/span><\/td>\n<\/tr>\n
    0000 1000<\/span><\/td>\n00<\/span>00 0111<\/span><\/span><\/td>\n0000 0000<\/span><\/span><\/td>\n<\/tr>\n
    0001\u00a00000<\/span><\/td>\n00<\/span>00 1111<\/span><\/span><\/td>\n0000 0000<\/span><\/span><\/td>\n<\/tr>\n
    ......<\/span><\/td>\n....<\/span>.<\/span>.<\/span><\/td>\n....<\/span>.<\/span>.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    \n
    \u4ee3\u7801\u5b9e\u73b0<\/span><\/p>\n
    \n
    class<\/span> Solution<\/span> <\/span>{<\/span><\/code>\n    public<\/span> boolean<\/span> isPowerOfTwo<\/span>(int<\/span> n)<\/span> <\/span>{<\/span><\/code>\n        if<\/span>(n <= 0<\/span>){<\/span><\/code>\n            return<\/span> false<\/span>;<\/span><\/code>\n        }<\/span><\/code>\n        return<\/span> (n & (n - 1<\/span>)) == 0<\/span>;<\/span><\/code>\n    }<\/span><\/code>}<\/span><\/code><\/pre>\n<\/section>\n
    \n
    \u590d\u6742\u5ea6\u5206\u6790<\/span><\/p>\n
    \u65f6\u95f4\u590d\u6742\u5ea6: O(1)\u3002<\/span><\/section>\n
    \u7a7a\u95f4\u590d\u6742\u5ea6: O(1)\u3002<\/span><\/section>\n
    \u00a0<\/span><\/section>\n
    \u89e3\u6cd5\u4e09\uff1aInteger.bitCount(n)<\/span><\/h2>\n
    <\/figure>\n
    <\/figure>\n
    \u89e3\u9898\u601d\u8def\u8fd8\u662f\u83b7\u53d6\u4e8c\u8fdb\u5236\u4e2d1\u7684\u4e2a\u6570\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528JDK\u81ea\u5e26\u65b9\u6cd5<\/span> Integer.bitCount(n)<\/span>\u00a0\u53bb\u83b7\u53d61\u7684\u4e2a\u6570\uff0c\u4e3a1\u5219\u8fd4\u56de <\/span>true<\/span>\uff0c\u5426\u5219\u8fd4\u56de <\/span>false<\/span>\u3002<\/span><\/p>\n
    \u00a0<\/span><\/p>\n
    \u4ee3\u7801\u5b9e\u73b0<\/span><\/p>\n
    \n
    class<\/span> Solution<\/span> <\/span>{<\/span><\/code>\n    public<\/span> boolean<\/span> isPowerOfTwo<\/span>(int<\/span> n)<\/span> <\/span>{<\/span><\/code>\n        if<\/span>(n <= 0<\/span>){<\/span><\/code>\n            return<\/span> false<\/span>;<\/span><\/code>\n        }<\/span><\/code>\n        return<\/span> Integer.bitCount(n) == 1<\/span> ? true<\/span> : false<\/span>;<\/span><\/code>\n    }<\/span><\/code>}<\/span><\/code><\/pre>\n<\/section>\n
    \n
    \u590d\u6742\u5ea6\u5206\u6790<\/span><\/p>\n
    \u65f6\u95f4\u590d\u6742\u5ea6 O(logN)\uff1aN\u4e3a\u4e8c\u8fdb\u5236\u4f4d\u6570\u3002\u590d\u6742\u5ea6\u5206\u6790\u53c2\u89c1\u8ba1\u7b97\u4e8c\u8fdb\u5236\u8868\u8fbe\u5f0f\u4e2d\u6570\u5b57\u4f4d\u6570\u4e3a \u20181\u2019 \u7684\u4e2a\u6570<\/a><\/span><\/p>\n
    \u7a7a\u95f4\u590d\u6742\u5ea6 O(1)\u3002<\/span><\/p>\n
    \n
    \u672c\u7bc7\u6587\u7ae0\u6765\u6e90\u4e8e\u5fae\u4fe1\u516c\u4f17\u53f7: i\u4f59\u6570<\/p><\/blockquote>\n<\/div>\n","raw":"","protected":false},"excerpt":{"rendered":"
    \u9898\u76ee \u7ed9\u4f60\u4e00\u4e2a\u6574\u6570 n\uff0c\u8bf7\u4f60\u5224\u65ad\u8be5\u6574\u6570\u662f\u5426\u662f 2 \u7684\u5e42\u6b21\u65b9\u3002\u5982\u679c\u662f\uff0c\u8fd4\u56de true \uff1b\u5426\u5219\uff0c\u8fd4\u56de false \u3002\u5982\u679c\u5b58\u5728\u4e00\u4e2a\u6574\u6570  …<\/p>\n","protected":false},"author":1,"featured_media":1527,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"emotion":"","emotion_color":"","title_style":"","license":"","footnotes":""},"categories":[22],"tags":[],"class_list":["post-1528","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-22"],"post_thumbnail_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230528043527136-150x150.jpeg","content_first_image":null,"post_medium_image_300":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230528043527136-300x128.jpeg","post_thumbnail_image_624":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230528043527136-1024x436.jpeg","post_frist_image":null,"post_medium_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230528043527136-300x128.jpeg","post_large_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230528043527136-1024x436.jpeg","post_full_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230528043527136.jpeg","post_all_images":[],"videoAdId":"","listAd":"0","listAdId":"","listAdEvery":6,"total_comments":0,"category_name":"\u7b97\u6cd5","post_date":"2023-05-28","like_count":"0","praiseWord":"\u9f13\u52b1","copyright_state":"","excitationAd":"0","rewardedVideoAdId":"","detailAdId":"","detailAd":"0","enterpriseMinapp":"0","audios":[],"postImageUrl":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230519082947553.jpg","avatarurls":[],"related_posts":null,"pageviews":233,"next_post_id":1608,"next_post_title":"\u3010\u7b97\u6cd5\u9898\u89e3\u301131. \u7ffb\u8f6c\u4e8c\u53c9\u6811\u7684\u9012\u5f52\u89e3\u6cd5","previous_post_id":null,"previous_post_title":null,"_links":{"self":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/1528","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/comments?post=1528"}],"version-history":[{"count":0,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/1528\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/media\/1527"}],"wp:attachment":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/media?parent=1528"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/categories?post=1528"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/tags?post=1528"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}