每天起床大喊一声，俺也一样。

int findIndex(int[] arr, int value) {
    int bg = 0, ed = arr.length - 1;
    while(bg <= ed) {
        int md = (ed - bg) / 2 + bg, mdv = arr[md];
        if (mdv == value) return md;
        if (mdv < value) bg = md + 1; 
        else ed = md - 1;
    }
    return -1;
}