Python3 解法, 执行用时: 46ms, 内存消耗: 7560K, 提交时间: 2023-03-31 10:17:14

n, t = map(int, input().split())
a = input()
try:
    a1,a2 = a.split('.')
    l = len(a1)
    a1 = int(a1)
    f = False
    while t:
        if a2[0] >='5':
            a1 +=1
            f = True
            break
        for i in range(len(a2)):
            if int(a2[i] )>= 5:
                a2 = a2[:i-1]+str(int(a2[i-1])+1)
                t -= 1
                break
        else:
            break
    if f:
        print(a1)
    else:
        print(str(a1)+'.'+a2)
except:
        print(a)

C++(clang++ 11.0.1) 解法, 执行用时: 3ms, 内存消耗: 472K, 提交时间: 2023-05-13 09:25:35

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,t;
	string a;
	cin>>n>>t>>a;
	int x=a.find('.');
	if(x==-1)
	{
		cout<<a;
		return 0;
	}
	for(int i=x+1;i<a.size();i++)
	{
		if(a[i]>='5')
		{
			a.erase(i);
			i--,t--;
			while(a[i]=='4'&&t)
			{
				a.erase(i);
				i--,t--;
			}
			if(a[i]=='.')
			{
				a.erase(i);
				i--;
				while(a[i]=='9')
				{
					a[i]='0';
					i--;
				}
				if(i==-1) cout<<1;
				else a[i]++;
			}
			else a[i]++;
		}
	}
	cout<<a;
} 

C++(g++ 7.5.0) 解法, 执行用时: 3ms, 内存消耗: 432K, 提交时间: 2023-01-16 01:11:18

#include<bits/stdc++.h>
using namespace std;
int main(){
	string a;
	int n,t,p;
	cin>>n>>t>>a;
	p=a.find('.');
	if(p==-1){
		cout<<a;return 0;
	}
	for(int i=p+1;i<a.size();i++){
		if(a[i]>='5'){
			a.erase(i);i--;t--;
			while(a[i]=='4'&&t){
				a.erase(i);i--;t--;
			}
			if(a[i]=='.'){
				a.erase(i);i--;
				while(a[i]=='9'){
					a[i]='0';i--;
				}
				if(i==-1)cout<<1;
				else a[i]++;
			}
			else a[i]++;
		}
	}
	cout<<a;
	return 0;
}