优化的javascript代码,在数组中找到3个最大的元素及其索引？

Question

我需要更优化的javascript代码才能找到数组中最大的3个元素.我试过这个代码.

var maxIndex = new Array();
var maxPoints = new Array();
var scoreByPattern = new Array(93,17,56,91,98,33,9,38,55,78,29,81,60);

function findLargest3(){ 

      maxPoints[0]=0;
      maxPoints[1]=0;
      maxPoints[2]=0;
    for(i=0;i < scoreByPattern.length; i++){        
        if( scoreByPattern[i] > maxPoints[0]){                               
             maxPoints[0] = scoreByPattern[i];
             maxIndex[0]=i;   
        }


    }

    for(i=0;i < scoreByPattern.length; i++){        
        if( scoreByPattern[i] > maxPoints[1] && scoreByPattern[i]< maxPoints[0] ){                               
             maxPoints[1] = scoreByPattern[i];
             maxIndex[1]=i;   
        }            
    }

    for(i=0;i < scoreByPattern.length; i++){        
        if( scoreByPattern[i] > maxPoints[2] && scoreByPattern[i]< maxPoints[1] ){                               
             maxPoints[2] = scoreByPattern[i];
             maxIndex[2]=i;   
        }            
    }

alert(scoreByPattern+"/******/"+maxPoints[0]+"/"+maxPoints[1]+"/"+maxPoints[2]);
//alert(maxIndex);
}

如何优化以上？(我需要最大数字的索引)是否有其他简单的方法来解决问题？

Answer 1

修改版

我修改了我的答案,使其更通用.它搜索数组中n个最大元素的索引:

var scoreByPattern = [93,255,17,56,91,98,33,9,38,55,78,29,81,60];

function findIndicesOfMax(inp, count) {
    var outp = [];
    for (var i = 0; i < inp.length; i++) {
        outp.push(i); // add index to output array
        if (outp.length > count) {
            outp.sort(function(a, b) { return inp[b] - inp[a]; }); // descending sort the output array
            outp.pop(); // remove the last index (index of smallest element in output array)
        }
    }
    return outp;
}

// show original array
console.log(scoreByPattern);

// get indices of 3 greatest elements
var indices = findIndicesOfMax(scoreByPattern, 3);
console.log(indices);

// show 3 greatest scores
for (var i = 0; i < indices.length; i++)
    console.log(scoreByPattern[indices[i]]);

这是一个jsFiddle

Answer 2

对数组进行降序排序,然后得到它的前三个元素:

var maxPoints = new Array();
var scoreByPattern = new Array(93,17,56,91,98,33,9,38,55,78,29,81,60);

findLargest3();

function findLargest3(){
    // sort descending
    scoreByPattern.sort(function(a,b) {
        if (a < b) { return 1; }
        else if (a == b) { return 0; }
        else { return -1; }
    });

    alert(scoreByPattern+"/******/"+scoreByPattern[0]+"/"+scoreByPattern[1]+"/"+scoreByPattern[2]);
}

示例小提琴

Answer 3

没有排序巨大的数组:O(n)考虑大数组运行.返回一个数组数组,[x,y]其中xvalue y是大数组中的值和索引.

var ar = [3,172,56,91,98,33,9,38,55,78,291,81,60];
console.log(`input is: ${ar}`);

function getMax(ar){
    if (ar.length < 3) return ar;
    var max = [[ar[0],0],[ar[1],1],[ar[2],2]],
        i,j;
    
    for (i = 3;i<ar.length;i++){
        for (j = 0;j<max.length;j++){
            if (ar[i] > max[j][0]){
                max[j] = [ar[i],i];
                if (j<2){
                    max.sort(function(a,b) { return a[0]-b[0]; });
                }
               break;            
            }
        }
    }
    return max;
}
result = getMax(ar);

console.log('output [number,index] is:');
console.log(result);