{"id":733,"date":"2008-08-14T09:53:26","date_gmt":"2008-08-14T01:53:26","guid":{"rendered":"http:\/\/www.yewen.us\/blog\/?p=733"},"modified":"2008-08-14T09:53:26","modified_gmt":"2008-08-14T01:53:26","slug":"%e5%bf%ab%e6%8e%92qsort%e7%9a%84%e7%94%a8%e6%b3%95%e8%af%a6%e8%a7%a3-%e4%b8%a4%e5%b9%b4%e5%89%8d%e7%9a%84%e5%8e%9f%e5%88%9b","status":"publish","type":"post","link":"https:\/\/www.yewen.us\/blog\/2008\/08\/%e5%bf%ab%e6%8e%92qsort%e7%9a%84%e7%94%a8%e6%b3%95%e8%af%a6%e8%a7%a3-%e4%b8%a4%e5%b9%b4%e5%89%8d%e7%9a%84%e5%8e%9f%e5%88%9b\/","title":{"rendered":"\u5feb\u6392qsort\u7684\u7528\u6cd5\u8be6\u89e3 (\u4e24\u5e74\u524d\u7684\u539f\u521b)"},"content":{"rendered":"

\u53d1\u4fe1\u4eba: snoopy (\u963f\u6392\/\u597d\u597d\u73a9ICPC~), \u4fe1\u533a: ACM_ICPC
\n\u6807 \u9898: \u5feb\u6392qsort\u7684\u7528\u6cd5\u8be6\u89e3
\n\u53d1\u4fe1\u7ad9: \u73de\u73c8\u5c71\u6c34BBS\u7ad9 (Sat Apr 29 21:02:35 2006), \u8f6c\u4fe1<\/p>\n

\u5f88\u591a\u4eba\u95ee\u8fd9\u4e2a\u4e1c\u897f.\u6211\u4ee5\u524d\u4e5f\u770b\u4e86\u597d\u4e45,\u4eca\u5929\u7ffb\u5230\u4ee5\u524d\u5b66\u5feb\u6392\u7684\u65f6\u5019\u5199\u7684\u7ec3\u4e60code,\u57fa\u672c\u4e0a
\n\u80fd\u8986\u76d6\u7edd\u5927\u90e8\u5206\u7528\u6cd5\u4e86.<\/p>\n

\u91cc\u9762\u6709\u5f88\u591a\u5730\u65b9\u6ca1\u5224\u65ad\u76f8\u7b49\u7684\u60c5\u51b5,\u6309\u9053\u7406\u6765\u8bf4\u76f8\u7b49\u60c5\u51b5\u4e0b\u5e94\u8be5\u8fd4\u56de0\u7684,\u8fd9\u4e2a\u8bf7\u770b\u4ee3\u7801\u7684
\n\u65f6\u5019\u6ce8\u610f.\u6211\u5c3d\u91cf\u4fdd\u8bc1\u4ee3\u7801\u4e0d\u51fa\u9519\u4e86.<\/p>\n

\u4e0b\u9762\u7684\u8fd9\u4e9b\u8bf4\u660e\u548c\u95ee\u9898\u90fd\u662f\u4e2a\u4eba\u539f\u521b,\u6ca1\u67e5\u4ec0\u4e48\u8d44\u6599,\u6240\u4ee5\u4e0d\u4fdd\u8bc1\u5176\u5b8c\u5168\u6b63\u786e\u6027,\u5728\u6b64\u8868\u793a\u4e2a
\n\u4eba\u4e0d\u5bf9\u51fa\u73b0\u7684\u95ee\u9898\u8d1f\u4efb\u4f55\u8d23\u4efb,\u5927\u5bb6WA\u4e86\u6216\u8005\u5e72\u5417\u7684\u4e0d\u8981\u602a\u6211,\u4e0d\u8fc7\u81f3\u5c11\u76ee\u524d\u6765\u8bf4\u6211\u7528\u8d77\u6765
\n\u662f\u6ca1\u95ee\u9898\u7684 :)<\/p>\n

\/*—————————————————————————-*\/<\/p>\n

** \u5173\u4e8e\u5feb\u6392\u51fd\u6570\u7684\u4e00\u4e9b\u8bf4\u660e **<\/p>\n

qsort,\u5305\u542b\u5728stdlib.h\u5934\u6587\u4ef6\u91cc,\u51fd\u6570\u4e00\u5171\u56db\u4e2a\u53c2\u6570,\u6ca1\u8fd4\u56de\u503c.\u4e00\u4e2a\u5178\u578b\u7684qsort\u7684\u5199\u6cd5\u5982\u4e0b<\/p>\n

qsort(s,n,sizeof(s[0]),cmp);<\/code><\/p>\n

\u5176\u4e2d\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u53c2\u4e0e\u6392\u5e8f\u7684\u6570\u7ec4\u540d(\u6216\u8005\u4e5f\u53ef\u4ee5\u7406\u89e3\u6210\u5f00\u59cb\u6392\u5e8f\u7684\u5730\u5740,\u56e0\u4e3a\u53ef\u4ee5\u5199&s[i]
\n\u8fd9\u6837\u7684\u8868\u8fbe\u5f0f,\u8fd9\u4e2a\u95ee\u9898\u4e0b\u9762\u6709\u8bf4\u660e); \u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u53c2\u4e0e\u6392\u5e8f\u7684\u5143\u7d20\u4e2a\u6570; \u7b2c\u4e09\u4e2a\u4e09\u6570\u662f
\n\u5355\u4e2a\u5143\u7d20\u7684\u5927\u5c0f,\u63a8\u8350\u4f7f\u7528sizeof(s[0])\u8fd9\u6837\u7684\u8868\u8fbe\u5f0f,\u4e0b\u9762\u4e5f\u6709\u8bf4\u660e :) ;\u7b2c\u56db\u4e2a\u53c2\u6570\u5c31\u662f
\n\u5f88\u591a\u4eba\u89c9\u5f97\u975e\u5e38\u56f0\u60d1\u7684\u6bd4\u8f83\u51fd\u6570\u5566,\u5173\u4e8e\u8fd9\u4e2a\u51fd\u6570,\u8fd8\u8981\u8bf4\u7684\u6bd4\u8f83\u9ebb\u70e6…<\/p>\n

\u6211\u4eec\u6765\u8ba8\u8bbacmp\u8fd9\u4e2a\u6bd4\u8f83\u51fd\u6570(\u5199\u6210cmp\u662f\u6211\u7684\u4e2a\u4eba\u559c\u597d,\u4f60\u53ef\u4ee5\u968f\u4fbf\u5199\u6210\u4ec0\u4e48,\u6bd4\u5982qcmp\u4ec0\u4e48
\n\u7684).\u5178\u578b\u7684cmp\u7684\u5b9a\u4e49\u662f<\/p>\n

int cmp(const void *a,const void *b);<\/code><\/p>\n

\u8fd4\u56de\u503c\u5fc5\u987b\u662fint,\u4e24\u4e2a\u53c2\u6570\u7684\u7c7b\u578b\u5fc5\u987b\u90fd\u662fconst void *,\u90a3\u4e2aa,b\u662f\u6211\u968f\u4fbf\u5199\u7684,\u4e2a\u4eba\u559c\u597d.
\n\u5047\u8bbe\u662f\u5bf9int\u6392\u5e8f\u7684\u8bdd,\u5982\u679c\u662f\u5347\u5e8f,\u90a3\u4e48\u5c31\u662f\u5982\u679ca\u6bd4b\u5927\u8fd4\u56de\u4e00\u4e2a\u6b63\u503c,\u5c0f\u5219\u8d1f\u503c,\u76f8\u7b49\u8fd4\u56de
\n0,\u5176\u4ed6\u7684\u4f9d\u6b21\u7c7b\u63a8,\u540e\u9762\u6709\u4f8b\u5b50\u6765\u8bf4\u660e\u5bf9\u4e0d\u540c\u7684\u7c7b\u578b\u5982\u4f55\u8fdb\u884c\u6392\u5e8f.<\/p>\n

\u5728\u51fd\u6570\u4f53\u5185\u8981\u5bf9a,b\u8fdb\u884c\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362\u540e\u624d\u80fd\u5f97\u5230\u6b63\u786e\u7684\u8fd4\u56de\u503c,\u4e0d\u540c\u7684\u7c7b\u578b\u6709\u4e0d\u540c\u7684\u5904\u7406
\n\u65b9\u6cd5.\u5177\u4f53\u60c5\u51b5\u8bf7\u53c2\u8003\u540e\u9762\u7684\u4f8b\u5b50.<\/p>\n

\/*—————————————————————————-*\/<\/p>\n

** \u5173\u4e8e\u5feb\u6392\u7684\u4e00\u4e9b\u5c0f\u95ee\u9898 **<\/p>\n

1.\u5feb\u6392\u662f\u4e0d\u7a33\u5b9a\u7684,\u8fd9\u4e2a\u4e0d\u7a33\u5b9a\u4e00\u4e2a\u8868\u73b0\u5728\u5176\u4f7f\u7528\u7684\u65f6\u95f4\u662f\u4e0d\u786e\u5b9a\u7684,\u6700\u597d\u60c5\u51b5(O(n))\u548c\u6700
\n\u574f\u60c5\u51b5(O(n^2))\u5dee\u8ddd\u592a\u5927,\u6211\u4eec\u4e00\u822c\u8bf4\u7684O(nlog(n))\u90fd\u662f\u6307\u7684\u662f\u5176\u5e73\u5747\u65f6\u95f4.<\/p>\n

2.\u5feb\u6392\u662f\u4e0d\u7a33\u5b9a\u7684,\u8fd9\u4e2a\u4e0d\u7a33\u5b9a\u8868\u73b0\u5728\u5982\u679c\u76f8\u540c\u7684\u6bd4\u8f83\u5143\u7d20,\u53ef\u80fd\u987a\u5e8f\u4e0d\u4e00\u6837,\u5047\u8bbe\u6211\u4eec\u6709
\n\u8fd9\u6837\u4e00\u4e2a\u5e8f\u5217,3,3,3,\u4f46\u662f\u8fd9\u4e09\u4e2a3\u662f\u6709\u533a\u522b\u7684,\u6211\u4eec\u6807\u8bb0\u4e3a3a,3b,3c,\u5feb\u6392\u540e\u7684\u7ed3\u679c\u4e0d\u4e00\u5b9a
\n\u5c31\u662f3a,3b,3c\u8fd9\u6837\u7684\u6392\u5217,\u6240\u4ee5\u5728\u67d0\u4e9b\u7279\u5b9a\u573a\u5408\u6211\u4eec\u8981\u7528\u7ed3\u6784\u4f53\u6765\u4f7f\u5176\u7a33\u5b9a(No.6\u7684\u4f8b\u5b50\u5c31
\n\u662f\u8bf4\u660e\u8fd9\u4e2a\u95ee\u9898\u7684)<\/p>\n

3.\u5feb\u6392\u7684\u6bd4\u8f83\u51fd\u6570\u7684\u4e24\u4e2a\u53c2\u6570\u5fc5\u987b\u90fd\u662fconst void *\u7684,\u8fd9\u4e2a\u8981\u7279\u522b\u6ce8\u610f,\u5199a\u548cb\u53ea\u662f\u6211\u7684
\n\u4e2a\u4eba\u559c\u597d,\u5199\u6210cmp\u4e5f\u53ea\u662f\u6211\u7684\u4e2a\u4eba\u559c\u597d.\u63a8\u8350\u5728cmp\u91cc\u9762\u91cd\u65b0\u5b9a\u4e49\u4e24\u4e2a\u6307\u9488\u6765\u5f3a\u5236\u7c7b\u578b\u8f6c\u6362,
\n\u7279\u522b\u662f\u5728\u5bf9\u7ed3\u6784\u4f53\u8fdb\u884c\u6392\u5e8f\u7684\u65f6\u5019<\/p>\n

4.\u5feb\u6392qsort\u7684\u7b2c\u4e09\u4e2a\u53c2\u6570,\u90a3\u4e2asizeof,\u63a8\u8350\u662f\u4f7f\u7528sizeof(s[0])\u8fd9\u6837,\u7279\u522b\u662f\u5bf9\u7ed3\u6784\u4f53,
\n\u5f80\u5f80\u81ea\u5df1\u5b9a\u4e492*sizeof(int)\u8fd9\u6837\u7684\u4f1a\u51fa\u95ee\u9898,\u7528sizeof(s[0)\u65e2\u65b9\u4fbf\u53c8\u4fdd\u9669<\/p>\n

5.\u5982\u679c\u8981\u5bf9\u6570\u7ec4\u8fdb\u884c\u90e8\u5206\u6392\u5e8f,\u6bd4\u5982\u5bf9\u4e00\u4e2as[n]\u7684\u6570\u7ec4\u6392\u5217\u5176\u4eces[i]\u5f00\u59cb\u7684m\u4e2a\u5143\u7d20,\u53ea\u9700\u8981
\n\u5728\u7b2c\u4e00\u4e2a\u548c\u7b2c\u4e8c\u4e2a\u53c2\u6570\u4e0a\u8fdb\u884c\u4e00\u4e9b\u4fee\u6539:qsort(&s[i],m,sizeof(s[i]),cmp);<\/p>\n

\/*—————————————————————————-*\/<\/p>\n

** \u6807\u7a0b,\u4e3e\u4f8b\u8bf4\u660e **<\/p>\n

No.1.\u624b\u5de5\u5b9e\u73b0QuickSort<\/p>\n

#include <stdio.h>\n\nint a[100],n,temp;\n\nvoid QuickSort(int h,int t)\n{\n     if(h>=t) return;\n     int mid=(h+t)\/2,i=h,j=t,x;\n     x=a[mid];\n     while(1)\n     {\n         while(a[i]<x) i++;\n         while(a[j]>x) j--;\n         if(i>=j) break;\n         temp=a[i];\n         a[i]=a[j];\n         a[j]=temp;\n     }\n     a[mid]=a[j];\n     a[j]=x;\n     QuickSort(h,j-1);\n     QuickSort(j+1,t);\n     return;\n}\n\nint main()\n{\n     int i;\n     scanf("%d",&n);\n     for(i=0;i<n;i++) scanf("%d",&a[i]);\n     QuickSort(0,n-1);\n     for(i=0;i<n;i++) printf("%d ",a[i]);\n\n     return(0);\n}<\/pre>\n
No.2.\u6700\u5e38\u89c1\u7684,\u5bf9int\u6570\u7ec4\u6392\u5e8f<\/p>\n
#include <stdio.h>\n#include <string.h>\n#include <stdlib.h>\n\nint s[10000],n,i;\n\nint cmp(const void *a, const void *b)\n{\n     return(*(int *)a-*(int *)b);\n}\n\nint main()\n{\n     scanf("%d",&n);\n     for(i=0;i<n;i++) scanf("%d",&s[i]);\n    \n     qsort(s,n,sizeof(s[0]),cmp);\n    \n     for(i=0;i<n;i++) printf("%d ",s[i]);\n    \n     return(0);\n}<\/pre>\n
No.3.\u5bf9double\u578b\u6570\u7ec4\u6392\u5e8f,\u539f\u7406\u540cint<\/p>\n
\u8fd9\u91cc\u505a\u4e2a\u6ce8\u91ca,\u672c\u6765\u662f\u56e0\u4e3a\u8981\u5224\u65ad\u5982\u679ca==b\u8fd4\u56de0\u7684,\u4f46\u662f\u4e25\u683c\u6765\u8bf4,\u4e24\u4e2adouble\u6570\u662f\u4e0d\u53ef\u80fd\u76f8\u7b49\u7684,\u53ea\u80fd\u8bf4fabs(a-b)<1e-20\u4e4b\u7c7b\u7684\u8fd9\u6837\u6765\u5224\u65ad,\u6240\u4ee5\u8fd9\u91cc\u53ea\u8fd4\u56de\u4e861\u548c-1\n[code lang=\"c\"]#include <stdio.h>\n#include <stdlib.h>\n\ndouble s[1000];\nint i,n;\n\nint cmp(const void * a, const void * b)\n{\n     return((*(double*)a-*(double*)b>0)?1:-1);\n}\n\nint main()\n{\n     scanf("%d",&n);\n     for(i=0;i<n;i++) scanf("%lf",&s[i]);\n    \n     qsort(s,n,sizeof(s[0]),cmp);\n    \n     for(i=0;i<n;i++) printf("%lf ",s[i]);\n    \n     return(0);\n} [\/code]\n\nNo.4.\u5bf9\u4e00\u4e2a\u5b57\u7b26\u6570\u7ec4\u6392\u5e8f.\u539f\u7406\u540cint\n[code lang=\"c\"]#include <stdio.h>\n#include <string.h>\n#include <stdlib.h>\n\nchar s[10000],i,n;\n\nint cmp(const void *a,const void *b)\n{\n     return(*(char *)a-*(char *)b);\n}\n\nint main()\n{\n     scanf("%s",s);\n     n=strlen(s);\n     qsort(s,n,sizeof(s[0]),cmp);\n    \n     printf("%s",s);\n     return(0);\n}[\/code]\n\nNo.5.\u5bf9\u7ed3\u6784\u4f53\u6392\u5e8f\n\n\u6ce8\u91ca\u4e00\u4e0b.\u5f88\u591a\u65f6\u5019\u6211\u4eec\u90fd\u4f1a\u5bf9\u7ed3\u6784\u4f53\u6392\u5e8f,\u6bd4\u5982\u6821\u8d5b\u9884\u9009\u8d5b\u7684\u90a3\u4e2a\u6a31\u82b1,\u4e00\u822c\u8fd9\u4e2a\u65f6\u5019\u90fd\u5728\ncmp\u51fd\u6570\u91cc\u9762\u5148\u5f3a\u5236\u8f6c\u6362\u4e86\u7c7b\u578b,\u4e0d\u8981\u5728return\u91cc\u9762\u8f6c,\u6211\u4e5f\u8bf4\u4e0d\u6e05\u4e3a\u4ec0\u4e48,\u4f46\u662f\u8fd9\u6837\u7a0b\u5e8f\u4f1a\n\u66f4\u6e05\u6670,\u5e76\u4e14\u7edd\u5bf9\u662f\u6ca1\u9519\u7684. \u8fd9\u91cc\u540c\u6837\u8bf7\u6ce8\u610fdouble\u8fd4\u56de0\u7684\u95ee\u9898\n\n[code lang=\"c\"]#include <stdio.h>\n#include <stdlib.h>\n\nstruct node\n{\n     double date1;\n     int no;\n} s[100];\n\nint i,n;\n\nint cmp(const void *a,const void *b)\n{\n     struct node *aa=(node *)a;\n     struct node *bb=(node *)b;\n     return(((aa->date1)>(bb->date1))?1:-1);\n}\n\nint main()\n{\n     scanf("%d",&n);\n     for(i=0;i<n;i++)\n     {\n         s[i].no=i+1;\n         scanf("%lf",&s[i].date1);\n     }\n     qsort(s,n,sizeof(s[0]),cmp);\n    \n     for(i=0;i<n;i++) printf("%d   %lfn",s[i].no,s[i].date1);\n    \n     return(0);\n}[\/code]\n\nNo.6.\u5bf9\u7ed3\u6784\u4f53\u6392\u5e8f.\u52a0\u5165no\u6765\u4f7f\u5176\u7a33\u5b9a(\u5373data\u503c\u76f8\u7b49\u7684\u60c5\u51b5\u4e0b\u6309\u539f\u6765\u7684\u987a\u5e8f\u6392)\n\n[code lang=\"c\"]#include <stdio.h>\n#include <stdlib.h>\n\nstruct node\n{\n     double date1;\n     int no;\n} s[100];\n\nint i,n;\n\nint cmp(const void *a,const void *b)\n{\n     struct node *aa=(node *)a;\n     struct node *bb=(node *)b;\n     if(aa->date1!=bb->date1)\n         return(((aa->date1)>(bb->date1))?1:-1);\n     else\n         return((aa->no)-(bb->no));\n}\n\nint main()\n{\n     scanf("%d",&n);\n     for(i=0;i<n;i++)\n     {\n         s[i].no=i+1;\n         scanf("%lf",&s[i].date1);\n     }\n     qsort(s,n,sizeof(s[0]),cmp);\n\n     for(i=0;i<n;i++) printf("%d   %lfn",s[i].no,s[i].date1);\n\n     return(0);\n} [\/code]\n\nNo.7.\u5bf9\u5b57\u7b26\u4e32\u6570\u7ec4\u7684\u6392\u5e8f(char s[][]\u578b)\n\n[code lang=\"c\"]#include <stdio.h>\n#include <string.h>\n#include <stdlib.h>\n\nchar s[100][100];\nint i,n;\n\nint cmp(const void *a,const void *b)\n{\n     return(strcmp((char*)a,(char*)b));\n}\n\nint main()\n{\n     scanf("%d",&n);\n     for(i=0;i<n;i++) scanf("%s",s[i]);\n\n    \n     qsort(s,n,sizeof(s[0]),cmp);\n    \n     for(i=0;i<n;i++) printf("%sn",s[i]);\n    \n     return(0);\n}[\/code]\n\nNo.8.\u5bf9\u5b57\u7b26\u4e32\u6570\u7ec4\u6392\u5e8f(char *s[]\u578b)\n[code lang=\"c\"]#include <stdio.h>\n#include <string.h>\n#include <stdlib.h>\n\nchar *s[100];\nint i,n;\n\nint cmp(const void *a,const void *b)\n\n{\n     return(strcmp(*(char**)a,*(char**)b));\n}\n\nint main()\n{\n     scanf("%d",&n);\n     for(i=0;i<n;i++)\n     {\n         s[i]=(char*)malloc(sizeof(char*));\n         scanf("%s",s[i]);\n     }\n\n     qsort(s,n,sizeof(s[0]),cmp);\n\n     for(i=0;i<n;i++) printf("%sn",s[i]);\n\n     return(0);\n}[\/code]\n<\/p>\n","protected":false},"excerpt":{"rendered":"
\u53d1\u4fe1\u4eba: snoopy (\u963f\u6392\/\u597d\u597d\u73a9ICPC~), \u4fe1\u533a: ACM_ICPC \u6807 \u9898: \u5feb\u6392qsort\u7684\u7528\u6cd5 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[7,11],"tags":[26,264],"class_list":["post-733","post","type-post","status-publish","format-standard","hentry","category-tech-notes","category-contests","tag-acm","tag-264"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p4aR5e-bP","_links":{"self":[{"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/posts\/733","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/comments?post=733"}],"version-history":[{"count":0,"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/posts\/733\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/media?parent=733"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/categories?post=733"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.yewen.us\/blog\/wp-json\/wp\/v2\/tags?post=733"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}