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55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
#define LOG_N 42
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static int delta[LOG_N];
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void make_delta(int N)
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{
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int power = 1;
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int i = 0;
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do
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{
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int half = power;
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power <<= 1;
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delta[i] = (N + half) / power;
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}
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while (delta[i++] != 0);
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}
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int unisearch(int *a, int key)
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{
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int i = delta[0]-1; /* midpoint of array */
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int d = 0;
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while (1)
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{
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if (key == a[i])
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{
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return i;
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}
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else if (delta[d] == 0)
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{
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return -1;
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}
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else
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{
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if (key < a[i])
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{
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i -= delta[++d];
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}
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else
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{
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i += delta[++d];
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}
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}
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}
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}
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#define N 10
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int main(void)
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{
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int num, a[N] = {1,3,5,6,7,9,14,15,17,19};
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make_delta(N);
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printf("\nEnter an element to search: ");
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scanf("%d", &num);
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printf("%d is at index %d\n", num, unisearch(a, num));
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return 0;
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} |