js 二分查找

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仿Java collections里的实现

var binarySearch = function(items, value, comp){
    var low = 0,
        high = items.length - 1,
        mid,
        tmpC;
    comp = comp || function(v, item) {
        return v < item ? -1 : (v > item ? 1 : 0);
    };
    while(low <= high && (tmpC = comp(value, items[mid = (high + low) >>> 1])) != 0){
        if (tmpC < 0){
            high = mid - 1;
        } else {
            low = mid + 1;
        }
    }
    return tmpC == 0 ? mid : (-low - 1);
}

 

 数值数组排序

numArr.sort(function(a,b) {
    return a - b
});

 有序数组去重

var uniqueOrderedArray = function (arr){
    var rs = [],
        preE,
        aLen = arr.length;
    if (aLen > 0) {
        preE = arr[0];
        rs.push(preE);
    }
    for(var i = 1; i < aLen; i++){
        if(arr[i] !== preE){
            preE = arr[i];
            rs.push(preE);
        }
    }
    return rs;
}