[js]从数组截取最大/最小的N个元素来求和

[VaJoy]

需求

• 完成两个函数minimumSum和maximumSum
• 它们都支持2个参数，第一个arr参数为数组，第二个参数num为Number类型
• 通过第二个参数num来决定要从数组里取多少个“最大”或者“最小”的元素来相加
• minimumSum将从数组里取最小的num个元素来相加，而maximumSum将从数组里取最大的num个元素来相加
• 不改变原数组

/* 示例：
 * var values = [1, 5, 12, 4, 3]
 * minimumSum(values, 2);   // => 1 + 3 = 4
 * maximumSum(values, 3);   // => 4 + 5 + 12 = 21
 *
 * param1 Array , param2 Number
 * return Number

 */

function minimumSum(arr, num) {
  //TODO：从arr里取num个最小的元素来相加，返回相加后的总和
}

function maximumSum(arr, num) {
  //TODO：从arr里取num个最大的元素来相加，返回相加后的总和
}

[bailnl]

######加了个需求，请不要改变原数组哈######


var values = [1, 5, 12, 4, 3];

function minimumSum(arr, num) {
    //TODO：从arr里取num个最小的元素来相加，返回相加后的总和
    return arr.slice(0).sort(function(a, b) {
        return a > b ? 1 : a < b ? -1 : 0
    }).slice(0, num).reduce(function(prev, current) {
        return prev + current
    }, 0)
}

function maximumSum(arr, num) {
    //TODO：从arr里取num个最大的元素来相加，返回相加后的总和
    return arr.slice(0).sort(function(a, b) {
        return a > b ? -1 : a < b ? 1 : 0
    }).slice(0, num).reduce(function(prev, current) {
        return prev + current
    }, 0)
}

[daqi]

/* 示例：
 * var values = [1, 5, 12, 4, 3]
 * minimumSum(values, 2);   // => 1 + 3 = 4
 * maximumSum(values, 3);   // => 4 + 5 + 12 = 21
 *
 * param1 Array , param2 Number
 * return Number

 */

function minimumSum(arr, num) {
  //TODO：从arr里取num个最小的元素来相加，返回相加后的总和

  var _arr = arr.slice().sort(function(a,b){return a>b?1:-1});
  var res = _arr.slice(0,num).reduce(function(p,c){return p+c});
  console.log(res);
}

function maximumSum(arr, num) {
  //TODO：从arr里取num个最大的元素来相加，返回相加后的总和
  var _arr = arr.slice().sort(function(a,b){return a>b?1:-1});
  var res = _arr.slice(-num,arr.length).reduce(function(p,c){return p+c});
  console.log(res);
}

[VaJoy]

加了个需求，请不要改变原数组哈

[bluesrocker]

@bailnl 师傅, 我来了

function minimumSum(arr/*, end*/){
    var argLeng = arguments.length;
    var sum = 0;
    if(argLeng>=1){
        if(Object.prototype.toString.call(arr)==='[object Array]'){
            var newArr = arr.map(Number);
            var numArr = [];
            for(var i=0, leng=newArr.length; i<leng; i++){
                if( !isNaN(newArr[i]) ){
                    numArr.push(newArr[i]);
                }
            }
            var sortedArr = numArr.sort( function(a, b){return a-b;} );
            var end = arguments[1];
            if(end === void 0){ end = leng; } //end缺省全部加上, 也可以考虑end缺省为0,看题目要求
            else{
                end = Number(end);
                end = isNaN(end) ? 0 : end;
                if(end<0){ //以原数组为基准, 不以sortedArr为基准
                    end = Math.max( Math.ceil(end)+leng, 0 );
                }
                else{ end = Math.min( Math.floor(end), leng ); }
            }
            for(var j=0; j<Math.min(end, sortedArr.length); j++){
                sum = sum + sortedArr[j];
            }
        }
    }
    return sum; //参数全部缺省或Math.min(end, sortedArr.length)=0时sum为0, 也可以考虑为NaN
};

function  maximumSum(arr/*, end*/){
    var argLeng = arguments.length;
    var sum = 0;
    if(argLeng>=1){
        if(Object.prototype.toString.call(arr)==='[object Array]'){
            var newArr = arr.map(Number);
            var numArr = [];
            for(var i=0, leng=newArr.length; i<leng; i++){
                if( !isNaN(newArr[i]) ){
                    numArr.push(newArr[i]);
                }
            }
            var sortedArr = numArr.sort( function(a, b){return b-a;} );
            var end = arguments[1];
            if(end === void 0){ end = leng; } //end缺省全部加上, 也可以考虑end缺省为0, 看题目要求
            else{
                end = Number(end);
                end = isNaN(end) ? 0 : end;
                if(end<0){ //以原数组为基准, 不以sortedArr为基准
                    end = Math.max( Math.ceil(end)+leng, 0 );
                }
                else{ end = Math.min( Math.floor(end), leng ); }
            }
            for(var j=0; j<Math.min(end, sortedArr.length); j++){
                sum = sum + sortedArr[j];
            }
        }
    }
    return sum; //参数全部缺省或Math.min(end, sortedArr.length)=0时sum为0, 也可以考虑为NaN
};

if(!Array.prototype.map){
    Array.prototype.map = function(callback/*, thisCB*/){
        'use strict';
        if(this===null || typeof this==='undefined'){
            throw new TypeError('Array.prototype.map'
                + ' is called on null or undefined');
        }
        if(typeof callback !== "function"){
            throw new TypeError(callback + ' is not a function');
        }
        var len = this.length>>>0;
        var res = new Array(len);
        var thisCB = arguments[1];
        for(var i=0; i<len; i++){
            if(i in this){
                res[i] = callback.call(thisCB, this[i], i, this);
            }
        }
        return res;
    }
};

[wanglianjie91]

    function minimunSun(arr,num){
        var newArr = [];
        for(var i = 0; i< arr.length;i++){
            newArr[i] = arr[i];
        }
        newArr.sort(function(m,n){
            return m-n;
        });
        var result = 0;
        for(var j = 0;j<num;j++){
            result+=newArr[j];
        }
        return result;
    }

    function maximunSum(arr,num){
        var newArr = [];
        var result = 0; 
        for(var i = 0; i< arr.length;i++){
            newArr[i] = arr[i];
        }
        for(var m = 0; m<newArr.length; m++){
            for(var n = m+1; n < newArr.length; n++){
                var p = newArr[n];
                if(newArr[m]<newArr[n]){
                    newArr[n] = newArr[m];
                    newArr[m] = p;
                }
            }
        }
        for(var j = 0; j < num; j++){
            result+=newArr[j];
        }
        return result;      
    }

[inJs]

        function sum(strategy, ary ,num) {
            if(num <= 0) {
                return NaN;
            }
            //防止死循环
            if(num > ary.length) {
                num = ary.length;
            }

            var copyOfAry = ary.slice(),
                    cursor = 1,
                    res = 0,
                    buffer = 0;

            while(cursor <= num) {
                buffer = Math[strategy].apply(this ,copyOfAry);
                res += buffer;
                copyOfAry.splice(copyOfAry.indexOf(buffer) ,1);

                cursor++;
            }

            return res;
        }

        function maximumSum(ary ,num) {
            return sum('max' ,ary ,num);
        }

        function minimumSum(ary ,num) {
            return sum('min' ,ary ,num);
        }

[inJs]

大熊的版本好牛逼， fuck!!

大熊的版本：

        function sum(fn ,ary ,num) {
            return eval(ary.slice().sort(fn).slice(0 ,num ).join('+'));
        }

        function minimumSum(ary ,num) {
            return sum(function(a ,b) {
                return a>b ? 1 : a<b ? -1 : 0;
            } ,ary ,num);
        }

        function maximumSum(ary ,num) {
            return sum(function(a, b) {
                return a>b ? -1 : a<b ? 1 : 0;
            } ,ary ,num);
        }

[tudousi]

/* 示例：
 * var values = [1, 5, 12, 4, 3]
 * minimumSum(values, 2);   // => 1 + 3 = 4
 * maximumSum(values, 3);   // => 4 + 5 + 12 = 21
 *
 * param1 Array , param2 Number
 * return Number
 */
var values = [1, 5, 12, 4, 3]
minimumSum(values, 2);
maximumSum(values, 2);
function minimumSum(arr, num) {
    //TODO：从arr里取num个最小的元素来相加，返回相加后的总和
    var s = arr.slice(0).sort(function(a,b){
        return a - b;
    });
    var t = s.slice(0,num).reduce(function(o, c) {
        return o + c;
    });
    console.log('min', t);
}
function maximumSum(arr, num) {
  //TODO：从arr里取num个最大的元素来相加，返回相加后的总和
    var s = arr.slice(0).sort(function(a,b){
        return b - a;
    });
    console.log(s);
    var t = s.slice(0,num).reduce(function(o, c) {
        return o + c;
    });
    console.log('max', t);
}

//

[wait-hua]

function maximumSum(arr, num) {
    if(num > arr.length) {
        return arr.reduce(function(prev, cur) {
            return prev + cur;
        })
    }
    var temp = arr.slice().sort(function(a, b){
        return b - a;
    });
    var sum = 0;
    for(var i=0; i<num; i++) {
        sum += temp[i];
    }
    return sum;
}   
function minimumSum(arr, num) {
    if(num > arr.length) {
        return arr.reduce(function(prev, cur) {
            return prev + cur;
        })
    }
    var temp = arr.slice().sort(function(a, b){
        return a - b;
    });
    var sum = 0;
    for(var i=0; i<num; i++) {
        sum += temp[i];
    }
    return sum;
}   

[Jiasm]

昂。。我觉得直接排序完了slice一下num然后进行加和求值就好了吧 /doge

(() => {
  /* 示例：
   * var values = [1, 5, 12, 4, 3]
   * minimumSum(values, 2);   // => 1 + 3 = 4
   * maximumSum(values, 3);   // => 4 + 5 + 12 = 21
   *
   * param1 Array , param2 Number
   * return Number

   */

  function minimumSum(arr, num) {
    //TODO：从arr里取num个最小的元素来相加，返回相加后的总和
    return func(arr, num, true)
  }

  function maximumSum(arr, num) {
    //TODO：从arr里取num个最大的元素来相加，返回相加后的总和
    return func(arr, num)
  }

  function func (arr, num, min) {
    return Array.from(arr).sort(min ? (a, b) => a - b : (a, b) => b - a).slice(0, num).reduce((result, item) => result + item, 0)
  }

  let values = [1, 5, 12, 4, 3]
  console.log(minimumSum(values, 2))   // => 1 + 3 = 4
  console.log(maximumSum(values, 3))   // => 4 + 5 + 12 = 21
})()