vector的erase无效

[woailaixiangnan]

洛谷的U35359
#include <bits/stdc++.h>
#include <vector>
using namespace std;
int main()
{
vector<int>v(100002);
int n,m,l;
cin>>n>>m;
for(int i = 1;i<=n;i++)
{
cin>>l;
v.push_back(l);
}
for(int i = 1;i<=m;i++)
{
int x=0,y=0;
char c;
cin>>c;
if(c == 'C')
{
cin>>x>>y;
v[x] -= y;
}
else if(c == 'D')
{
cin>>x;
v.erase(v.begin()+x);
}
else if(c == 'I')
{
cin>>x>>y;
v.erase(v.begin()+x);
v.insert(v.begin()+x,y);
}
else if(c == 'Q')
{
int sum;
sum = 0;
for(vector<int>::iterator it = v.begin() ; it !=v.end() ; it++)
{
sum+=*it;
}
cout<<sum<<endl;
}
}
return 0;
}

[啊大1号]

楼主代码里的erase是有效的。注意push.back是从最后插入元素。
举例：

#include <iostream>
#include <vector>
using namespace std;

int main()
{	
	vector<int> v(10);
	v.push_back(6);
	v.push_back(7);
	for (auto i : v)
		cout << i << " ";
	cout << endl;
	cout << "------华丽丽的分割线-----" << endl;

	v.erase(v.begin() + 1);
	
	for (auto i : v)
		cout << i << " ";
	cout << endl;

	return 0;
}

[starytx]

插入、删除操作多的情况选用list

[玉生香]

#include <vector>
using namespace std;
int main()
{
	
	int n, l,m=1;
	cin >> n ;
	vector<int>v(n,0);/*初始化大小*/ 
	for (int i = 0;i < n;i++) /*每个单位赋值*/
	{
		cin >> l;
		v[i]=l;
	}
	while(m) /*循环*/
	{
		int x = 0, y = 0;
		char c;
		cin >> c;

		switch (c)
		{
		case 'C':
			cin >> x >> y;
			if(x<(int)v.size() && 0 <= x) v[x] -= y;
			break;
		case 'D':
			cin >> x;
			if (x<(int)v.size() && 0 <= x) v.erase(v.begin() + x);
			break;
		case 'I':
			cin >> x >> y;
			if (x<(int)v.size() && 0 <= x) v.erase(v.begin() + x);
			if (x<(int)v.size() && 0 <= x) v.insert(v.begin() + x, y);
			else v.push_back(y);
			break;
		case 'Q':
			int sum;
			sum = 0;
			for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
			{
				sum += *it;
			}
			cout << sum << endl;
			break;

		case 'q': /*退出循环*/
			m = 0;
			cout << "/*退出循环*/" << endl;
			break;

		default:
			break;

		}
	}
	return 0;
}

引用 3 楼 starytx 的回复:

插入、删除操作多的情况选用list

版主正解

vector<int>v(100002); 这样删除一个，插入一个节点，内存移动，消耗大