function (a, x, lo, hi) {
    while (lo < hi) {
        var mid = lo + hi >>> 1;
        if (a[mid][1] < x) {
            lo = mid + 1;
        }
        else {
            hi = mid;
        }
    }
    return lo;
}
function (a, x, lo, hi) {
    while (lo < hi) {
        var mid = lo + hi >>> 1;
        if (a[mid][1] < x) {
            lo = mid + 1;
        }
        else {
            hi = mid;
        }
    }
    return lo;
}
function ( a , x , lo , hi ) { while ( lo < hi ) { var mid = lo + hi >>> 1 ; if ( a [ mid ] [ 1 ] < x ) { lo = mid + 1 ; } else { hi = mid ; } } return lo ; }
FIXME 公用？
FIXME 公用？
returns the index of the first element of a array that is less than x