Codeforces Round #756 (Div. 3)
date：2021/11/28
题意：
求最大连续区间长度，使其和 > = − s >=-s >=−s;
思路
1.双指针
重要的是双指针如何运动；
code
// Problem: F. ATM and Students
// Contest: Codeforces - Codeforces Round #756 (Div. 3)
// URL: https://codeforces.com/contest/1611/problem/F
// Memory Limit: 256 MB
// Time Limit: 2000 ms
//
// Powered by CP Editor (https://cpeditor.org)
#include<bits/stdc++.h>
using namespace std;
#define _orz ios::sync_with_stdio(false),cin.tie(0)
#define mem(str,num) memset(str,num,sizeof(str))
#define forr(i,a,b) for(int i = a;i <= b;i++)
#define forn(i,n) for(int i = 0; i < n; i++)
#define all(a) (a.begin(),a.end())
#define dbg() cout << "0k!" << endl;
//#define _DEBUG
typedef long long ll;
const int inf = 0x3f3f3f3f;
const int N = 1e6+10;
const ll MOD = 1e9+7;
void so1ve(){
int n,m;
cin >> n >>m;
vector<int> a(n+1);
forr(i,1,n) cin >> a[i];
int l = 1, r = 1;
ll lx = 0,rx = 0,now = 0,res = 0;
while(l <= n && r <= n){
while(m+now+a[r] >= 0 && r <= n) now += a[r++];
if(r-l > res){
res = r - l;
lx = l;
rx = r - 1;
}
now -= a[l++];
}
if(rx == 0 && lx == 0) puts("-1");
else cout << lx <<" " << rx << endl;
}
int main()
{
#ifdef _DEBUG
//freopen("input.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t; cin >> t;
while(t--) so1ve();
return 0;
}
2.后缀和+二分
思维较高
思路后补…
// Problem: F. ATM and Students
// Contest: Codeforces - Codeforces Round #756 (Div. 3)
// URL: https://codeforces.com/contest/1611/problem/F
// Memory Limit: 256 MB
// Time Limit: 2000 ms
//
// Powered by CP Editor (https://cpeditor.org)
#include<bits/stdc++.h>
using namespace std;
#define _orz ios::sync_with_stdio(false),cin.tie(0)
#define mem(str,num) memset(str,num,sizeof(str))
#define forr(i,a,b) for(int i = a;i <= b;i++)
#define forn(i,n) for(int i = 0; i < n; i++)
#define all(a) (a.begin(),a.end())
#define dbg() cout << "0k!" << endl;
//#define _DEBUG
using ll = long long;
const int inf = 0x3f3f3f3f;
const int N = 2e5+10;
const ll MOD = 1e9+7;
struct node{
ll val,id;
bool operator < (const node &t)const{
return val > t.val;
}
}t[N];
ll a[N];
set<int> s;
void so1ve(){
int n,m;cin >> n >> m;
forr(i,1,n) cin >> a[i];
a[++n] = -(1LL << 60LL);
a[++n] = 0;
for(int i = n; i;i--){
t[i].val = a[i];
if(i != n) t[i].val += t[i+1].val;
t[i].id = i;
}
sort(t + 1,t + 1 + n);
s.clear();
int l = 1,lx = 0,rx = -1;
forr(i,1,n){
for(;l <= n && t[l].val > t[i].val+m;l++)
s.insert(t[l].id);
auto it = s.lower_bound(t[i].id);
int x = t[i].id,y = *it - 2;
cout << x <<" " << y << endl;
if(y-x > rx - lx){
lx = x;
rx = y;
}
}
if(lx > rx) cout << -1 << endl;
else cout << lx <<" " << rx << endl;
}
int main()
{
#ifdef _DEBUG
//freopen("input.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t; cin >> t;
while(t--) so1ve();
return 0;
}