查找算法

// 循环实现int binarySearch(int *a, int len, int x) {    int low = 0;    int high = len-1;    int mid;    while (low <= high) {        mid = (low + high) / 2;        if (a[mid] < x)            low = mid + 1;        else if (a[mid] > x)             high = mid - 1;        else {            printf("found: a[%d]=%d\n", mid, a[mid]);            return mid;        }    }    printf("notfound\n");    return -1;}

// 递归实现int binarySearchRecursive(int *a, int x, int low, int high) {    if (low > high)        return -1;    int mid = (low + high) / 2;    if (a[mid] < x)        return binarySearchRecursive(a, x, mid+1, high);    else if (a[mid] > x)        return binarySearchRecursive(a, x, low, mid-1);    else        return mid;}int binarySearchRecursive(int *a, int len, int x) {    int ind = binarySearchRecursive(a, x, 0, len-1);    if (ind == -1)        printf("notfound\n");    else        printf("found: a[%d]=%d\n", ind, a[ind]);    return ind;}

此外查找的算法还有平衡二叉树、红黑树，hash等等