973.最接近原点的K个点

973.最接近原点的K个点

var kClosest = function(points, k) {
    let n=points.length;
    if(k>n){
        return points;
    }
    let dists=new Array(n).fill(null);
    for(let i=0;i<n;++i){
        dists[i]=dist(points[i])  
    }
    dists.sort((a,b)=>a-b);
    let distK=dists[k-1];
    let ans=[]
    let t=0;
    for(let i=0;i<n;i++){
        if(dist(points[i])<=distK){
            ans[t++]=points[i];
        }
    }
    return ans
};
function dist(point){
    return point[0]*point[0]+point[1]*point[1]
}


//class 版本
class Solution {
    kClosest(points, K) {
        const N = points.length;
        const dists = new Array(N);
        for (let i = 0; i < N; ++i)
            dists[i] = this.dist(points[i]);

        dists.sort((a, b) => a - b);
        const distK = dists[K - 1];

        const ans = [];
        let t = 0;
        for (let i = 0; i < N; ++i)
            if (this.dist(points[i]) <= distK)
                ans[t++] = points[i];
        return ans;
    }

    dist(point) {
        return point[0] * point[0] + point[1] * point[1];
    }
}

const s = new Solution();
const points = [[3, 3], [5, -1], [-2, 4]];
console.log(s.kClosest(points, 2));

//简化版
var kClosest = function(points, k) {
    // 直接在points上进行原地操作，根据欧几里得距离的平方进行排序
    points.sort((a, b) => (a[0]*a[0] + a[1]*a[1]) - (b[0]*b[0] + b[1]*b[1]));
    // 返回前k个元素
    return points.slice(0, k);
};

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