70 lines
1.5 KiB
C
70 lines
1.5 KiB
C
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#include <stdio.h>
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#define SIZE 1000000
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#define X 2*((SIZE-1) / 2) + 1
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#define T 10000000
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int binsearch(int x, int v[], int n);
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int binsearch_old(int x, int v[], int n);
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/* run binsearch on array of size SIZE
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* if arg is provided use old binsearch */
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int main(int argc, char *argv[])
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{
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long i;
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int arr[SIZE];
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for (i = 0; i < SIZE; ++i)
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arr[i] = 2 * i;
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if (argc == 1) {
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for (i = 0; i < T; ++i)
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binsearch(X, arr, SIZE);
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printf("binsearch : %d\n", binsearch(X, arr, SIZE));
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}
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else {
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for (i = 0; i < T; ++i)
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binsearch_old(X, arr, SIZE);
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printf("old binsearch : %d\n", binsearch_old(X, arr, SIZE));
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}
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return 0;
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}
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/* binsearch: find x in sorted v of length n, using one comparison in loop */
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int binsearch(int x, int v[], int n)
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{
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int low, high, mid;
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low = 0;
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high = n - 1;
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while (low < high) {
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mid = (low + high) / 2;
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if (x <= v[mid])
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high = mid;
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else
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low = mid + 1;
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}
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if (v[low] == x)
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return low;
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return -1;
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}
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/* binsearch: find x in sorted v of length n, using two comparisons in loop */
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int binsearch_old(int x, int v[], int n)
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{
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int low, high, mid;
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low = 0;
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high = n - 1;
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while (low <= high) {
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mid = (low + high) / 2;
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if (x < v[mid])
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high = mid - 1;
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else if (x > v[mid])
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low = mid + 1;
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else
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return mid;
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}
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return -1;
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}
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