1 /*第一种，就是写二分函数 2 因为要按照a数组的顺序输出，那么则把b数组排序之后进行二分查找 3 若a中该元素存在b数组，则输出即可 4 */ 5 #include<stdio.h> 6 #include<stdlib.h> 7 #include<string.h> 8 9 int binary_search(int* a, int x, int left, int right);//二分查找 10 int cmp(const void* a, const void* b);//快排的cmp函数 11 12 int a[100001] = { 0 }, b[100001] = { 0 }; 13 14 int main(void) { 15 int n, m; 16 17 scanf("%d %d", &n, &m); 18 for (int i = 0; i < n; i++) scanf("%d", &a[i]); 19 for (int i = 0; i < m; i++) scanf("%d", &b[i]); 20 qsort(b, m, sizeof(int), cmp); 21 22 int flag = 0;//空格处理 23 for (int i = 0; i < n; i++) { 24 if (binary_search(b, a[i], 0, m - 1)) { 25 if (!flag) { printf("%d", a[i]); flag = 1; } 26 else printf(" %d", a[i]); 27 } 28 } 29 30 return 0; 31 } 32 33 int cmp(const void* a, const void* b) { 34 return *(int*)a - *(int*)b; 35 } 36 37 int binary_search(int* a, int x, int left, int right) { 38 int mid; 39 while (left <= right) { 40 mid = (right + left) >> 1;// 除二 41 if (a[mid] == x) return 1; 42 else if (a[mid] > x) right = mid - 1; 43 else left = mid + 1; 44 } 45 return 0; 46 }
1 /*第二中，用C++ STL中的Binary search，存在返回真，否则假
2 因为要按照a数组的顺序输出，那么则把b数组排序之后进行二分查找 3 若a中该元素存在b数组，则输出即可 4 */ 5 #include<stdio.h> 6 #include<stdlib.h> 7 #include<string.h> 8 #include<algorithm> 9 using namespace std; 10 11 int cmp(const void* a, const void* b);//快排的cmp函数 12 13 int a[100001] = { 0 }, b[100001] = { 0 }; 14 15 int main(void) { 16 int n, m; 17 18 scanf("%d %d", &n, &m); 19 for (int i = 0; i < n; i++) scanf("%d", &a[i]); 20 for (int i = 0; i < m; i++) scanf("%d", &b[i]); 21 qsort(b, m, sizeof(int), cmp); 22 23 int flag = 0;//空格处理 24 for (int i = 0; i < n; i++) { 25 if (binary_search(b, b + m, a[i])) { 26 if (!flag) { printf("%d", a[i]); flag = 1; } 27 else printf(" %d", a[i]); 28 } 29 } 30 31 return 0; 32 } 33 34 int cmp(const void* a, const void* b) { 35 return *(int*)a - *(int*)b; 36 }