插值法查找

#include <stdio.h>  
#include <time.h>  


#define SIZE 20  


void print_array(int a[], int len)  
{  
    int i = 0;  
    for (i = 0; i < len; i++){  
        printf("%d,", a[i]);  
    }  
    printf("\n");  
}  
void swap(int a[], int i, int j)  
{  
    int temp = a[i];  
    a[i] = a[j];  
    a[j] = temp;  
}  

void selection_sort(int a[],int len)  
{  
    int i = 0;  
    int j = 0;  
    for (i = 0; i < len; i++){  
        for (j = i; j < len;j++){  
            if (a[j] < a[i]){  
                swap(a,i,j);  
            }  
        }  
    }  
}  

int binary_search_interpolation(int a[], int low, int high, int key)  
{  
    int ret = -1;  

    while ((low <= high) && (a[low] <= key) && (key <= a[high])){  
        float fx = 1.0f * (key - a[low]) / (a[high] - a[low]);  
        int mid = low + fx * (high - low);  
        if (a[mid] == key){  
            ret = mid;  
            break;  
        }  
        else if (a[mid] > key){  
            high = mid - 1;  
        }  
        else{  
            low = mid + 1;  
        }  
        printf("%d\n", mid);  
    }  

    return ret;  
}  


int main(void){  
    int a[SIZE] = { 0 };  
    int i = 0;  
    int key = 0;  
    int index = -1;  

    srand((unsigned int)time(NULL));  

    for (i = 0; i < SIZE; i++){  
        a[i] = rand() % 100;  
    }  

    key = rand() & 100;  

    printf("Static Search Demo\n");  
    printf("Key: %d\n", key);  
    printf("Array: \n");  
    print_array(a, SIZE);  
    selection_sort(a,SIZE);  
    print_array(a, SIZE);  
    index = binary_search_interpolation(a, 0,SIZE, key);  
    if (index >= 0){  
        printf("SUCCED: a[%d] = %d\n", index, a[index]);  
    }  
    else{  
        printf("Failed!!\n");  
    }  

    system("PAUSE");  
    return 0;  
}