JavaScript的简单算法练习

电玩女神 2022-05-19 03:46 159阅读 0赞

/**
     * 1.打印矩阵
     */
    function getMatrix(num){
        for(let i = 0; i < num; i++){
            let str = "";
            for(let j = 0; j < num; j++){
                str += "* "
            }
            console.log(str);
        }
    }
    
     getMatrix(3);

/**
     * 2.乘法表
     */
    function multiplicaiton(n){
        for(let i = 1; i <= n; i++){
            let str = "";
            for(let j = 1; j <= i; j++){
                str += `${i}*${j}=${i*j}  `;
            }
            console.log(str);
        }
    }
    
     multiplicaiton(9);

/**
     * 3.打印费氏级数
     */
    
    function fibonacci(n) {
    
        if(n < 0){
            return 0;
        }
        if(n == 0){
            return 0;
        }else if(n == 1){
            return 1;
        }else{
            return arguments.callee(n-1) + arguments.callee(n-2);
        }
    }
    
     console.log(fibonacci(8));

/**
     *  4.二分查找
     */
    function binarySearch(m,data) {
        let position = -1;
        let start = 0, end = data.length - 1;
        let mid = 0;
        while(start <= end) {
            mid = Math.floor((start + end) / 2);
            if(m > data[mid]) {
                start = mid + 1;
            }else if(m < data[mid]){
                end = mid - 1;
            }else {
                position = mid;
                break;
            }
        }
        return position;
    }
    
    let ms = [1,2,6,8,10];
    console.log(binarySearch(1, ms));
    console.log(binarySearch(6, ms));
    console.log(binarySearch(10, ms));

/**
     * 5.冒泡排序
     */
    function bubbleSort(arr) {
        let temp = 0;
        let flag = true;
        for(let i = 0; i < arr.length - 1 && flag; i++) { //若flag为true则退出循环
            flag = false;
            for (let j = 0; j < arr.length - 1 - i; j++) {
                if(arr[j] > arr[j + 1]) {
                    temp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = temp;
                    flag = true;
                }
            }
        }
    }
    let array = [3,4,1,8,5,9];
    bubbleSort(array);
    console.log(array);

/**
     * 6.选择排序
     */
    function selectSort(arr) {
        let minIndex,temp = 0;
        for(let i = 0; i < arr.length - 1; i++) {
            minIndex = i;  //将当前下标定义为最小值下标
            for (let j = i + 1; j < arr.length; j++) {
                if(arr[i] > arr[j]) {
                    //如果有小于当前最小值的关键值,将此关键值的下标赋值给min
                    minIndex = j;
                }
            }
            if(i != minIndex) {
                若min不等于i，说明找到最小值，交换
                temp = arr[i];
                arr[i] = arr[minIndex];
                arr[minIndex] = temp;
            }
        }
    
    }
    let array2 = [3,4,1,8,5,9];
    selectSort(array2);
    console.log(array2);

/**
     * 7.使用reduce计算二维数组中全部数值的和
     * 方法一：全部使用reduce
     */
    let arr2 = [[1,2,3],[4,5,6],[7,8,9,10]];
    let result = 0;
    arr2.reduce(function(prev,cur){
        result += [prev != undefined ? prev.reduce((prev,cur) => prev + cur) : 0,cur != undefined ? cur.reduce((prev,cur) => prev + cur) : 0].reduce((prev,cur) => prev + cur);
    });
    console.log(result);

/**
     * 7.使用reduce计算二维数组中全部数值的和
     * 方法二：使用map
     */
    let arr2 = [[1,2,3],[4,5,6],[7,8,9,10]];
    let result = arr2.map((item)=> item.reduce((prev,cur) => prev + cur)).reduce((prev,cur) => prev + cur);
    console.log(result);