二分法查找

有序数组二分法查找，找到则返回索引，否则返回-1

// 有序数组二分查找5
public int selfQuery() {
    int[] orderedArray = {1, 1, 2, 3, 3, 5, 7, 9, 9};
    int p = 0;
    int r = orderedArray.length;
    int q;
    while (p <= r) {
        q = (p + r) / 2;
        if (orderedArray[q] == 5) {
            return q;
        } else if (orderedArray[q] < 5) {
            p = q + 1;
        } else {
            r = q - 1;
        }
    }
    return -1;
}

 二分查找的时间为O(logN)级别