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Lesson4_1.java
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41 lines (30 loc) · 1.24 KB
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public class Lesson4_1 {
/**
* @Description: 算算舍罕王给了多少粒麦子
* @param grid-放到第几格
* @return long-麦粒的总数
*/
public static long getNumberOfWheat(int grid) {
long sum = 0; // 麦粒总数
long numberOfWheatInGrid = 0; // 当前格子里麦粒的数量
numberOfWheatInGrid = 1; // 第一个格子里麦粒的数量
sum += numberOfWheatInGrid;
for (int i = 2; i <= grid; i ++) {
numberOfWheatInGrid *= 2; // 当前格子里麦粒的数量是前一格的2倍
sum += numberOfWheatInGrid; // 累计麦粒总数
}
return sum;
}
public static void main(String[] args) {
int grid = 63;
long start, end = 0;
start = System.currentTimeMillis();
System.out.println(String.format("舍罕王给了这么多粒：%d", Lesson4_1.getNumberOfWheat(grid)));
end = System.currentTimeMillis();
System.out.println(String.format("耗时%d毫秒", (end - start)));
start = System.currentTimeMillis();
System.out.println(String.format("舍罕王给了这么多粒：%d", (long)(Math.pow(2, grid)) - 1));
end = System.currentTimeMillis();
System.out.println(String.format("耗时%d毫秒", (end - start)));
}
}