NOIP2012 借教室 题解 洛谷P1083

int left=1,right=m;
    while(left<right)//二分 
    {
        int mid=(left+right)>>1;
        if(check(mid)) left=mid+1;
        else right=mid;
    }

bool check(int x)//差分,判断 
{
    memset(f,0,sizeof(f));
    for(int i=1;i<=x;i++)
    {
        f[l[i]]+=d[i]; 
        f[r[i]+1]-=d[i];
    }
    for(int i=1;i<=n;i++)
    {
        g[i]=g[i-1]+f[i];
        if(a[i]<g[i]) 
        return 0;
    }
    return 1;
}

#include<iostream>
#include<stdio.h>
#include<math.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
using namespace std;
const int maxn=1e6+5;
int a[maxn],l[maxn],r[maxn],d[maxn],f[maxn],g[maxn],n,m;
bool check(int x)//差分,判断 
{
    memset(f,0,sizeof(f));
    for(int i=1;i<=x;i++)
    {
        f[l[i]]+=d[i]; 
        f[r[i]+1]-=d[i];
    }
    for(int i=1;i<=n;i++)
    {
        g[i]=g[i-1]+f[i];
        if(a[i]<g[i]) 
        return 0;
    }
    return 1;
}
signed main()
{
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    cin>>n>>m;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    for(int i=1;i<=m;i++)
        cin>>d[i]>>l[i]>>r[i];
    if(check(n)) 
    {
        cout<<"0"; 
        return 0;
    }
    else cout<<"-1"<<endl;
      int left=1,right=m;
    while(left<right)//二分 
    {
        int mid=(left+right)>>1;
        if(check(mid)) left=mid+1;
        else right=mid;
    }
    cout<<left;
    return 0;
}