codeforces 339B Xenia and Ringroad 解题报告

最新推荐文章于 2021-05-14 13:32:07 发布

AC_Lee

最新推荐文章于 2021-05-14 13:32:07 发布

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在一个由n个房屋组成的环形道路上，Xenia需要完成m项任务，每项任务需要她在特定的房屋中完成。从第1号房屋出发，求最小时间完成所有任务。移动相邻房屋需1单位时间。

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Xenia lives in a city that has n houses built along the main ringroad. The ringroad houses are numbered 1 through n in the clockwise order. The ringroad traffic is one way and also is clockwise.

Xenia has recently moved into the ringroad house number 1. As a result, she's got m things to do. In order to complete the i-th task, she needs to be in the house number ai and complete all tasks with numbers less than i. Initially, Xenia is in the house number 1, find the minimum time she needs to complete all her tasks if moving from a house to a neighboring one along the ringroad takes one unit of time.

Input

The first line contains two integers n and m (2 ≤ n ≤ 105, 1 ≤ m ≤ 105). The second line contains m integers a1, a2, ..., am (1 ≤ ai ≤ n). Note that Xenia can have multiple consecutive tasks in one house.

Output

Print a single integer — the time Xenia needs to complete all tasks.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64dspecifier.

Examples

input
4 3
3 2 3

output
6

input
4 3
2 3 3

output
2

Note

In the first test example the sequence of Xenia's moves along the ringroad looks as follows: 1 → 2 → 3 → 4 → 1 → 2 → 3. This is optimal sequence. So, she needs 6 time units.

水题

注意int和__int64之间需要显式类型转换，否则第七组数据过不去。。。

代码：

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

int a[100019];

int main () {
    int n,m;
    __int64 ans;
    while(~scanf("%d%d",&n,&m)){
    	for(int i=0;i<m;i++){
    		scanf("%d",&a[i]);
    	}
    	int num=0;
    	for(int i=1;i<m;i++){
    		if(a[i]<a[i-1]) num++;
    	}
    	ans=(__int64)num*(__int64)n+(__int64)a[m-1]-1;
    	printf("%I64d\n",ans);
    }
    return 0;
}