47 lines
1 KiB
C
47 lines
1 KiB
C
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#include <stdio.h>
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//函数功能：二分查找
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//函数参数：分别为被查找的数组，数组长度，所查找的元素
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//函数返回值：如果找到，则返回该元素在数组中的下标，否则返回-1
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int BinarySearch(int a[], int n, int key);
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int main() {
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int num
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[2000000]; //这个数组比较大，如果在你的电脑中无法分配这么大的内存，请改小后测试。
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int n, m, i;
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int key;
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scanf("%d%d", &n, &m);
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for (i = 0; i < n; i++)
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scanf("%d", &num[i]);
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for (i = 0; i < m; i++) {
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scanf("%d", &key);
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printf("%d", BinarySearch(num, n, key));
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if (i != m - 1)
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printf(" ");
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else
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printf("\n");
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}
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return 0;
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}
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/* 请在这里填写答案 */
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int BinarySearch(int a[], int n, int key) {
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int mid;
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int l = 0, r = n - 1;
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while (r >= l) {
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mid = (l + r) / 2;
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if (a[mid] == key) {
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return mid;
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} else if (a[mid] > key) {
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// Search left
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r = mid - 1;
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} else {
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// search right
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l = mid + 1;
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}
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}
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return -1;
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}
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