乘方--java递归实现--循环实现

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1.主程序

package recursion;//计算乘方public class Power {static long temp=1;        //--------递归实现乘方计算，时间O(logN)---------

public long calculate(long x, int y) {if (y == 1) {return x * temp;}if (y == 2) {return (x * x * temp);}if (y % 2 == 1) {temp = x;}return calculate(x * x, y / 2);}// ------------递归实现乘方，时间O（N）------------------------public long calculate2(long x, int y) {if (y == 1) {return x;} elsereturn x * calculate2(x, y - 1);}        //--------------循环实现乘方，时间O（N）------------------public long calculate3(long x, int y) {long result = 1;for (int i = 0; i < y; i++) {result = result * x;}return result;}}

2.测试程序

import recursion.Power;public class App {/** * @param args */public static void main(String[] args) {Power power = new Power();long result = power.calculate(5, 10);System.err.println(result);// ----------------------------result = power.calculate2(5, 10);System.err.println(result);// --------------------result = power.calculate3(5, 10);System.err.println(result);}}

3.测试结果

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