P1083 [NOIP2012 提高组] 借教室

#include <iostream>
using namespace std;
const int N = 1e6 + 1 ;
int n , m;
int a [ N ] ;
struct node {
    int tag , sum ;
    node(){ tag = sum = 0 ; }
    void init ( int x , int y ) { tag = x , sum = y ; }
};
namespace xds {
    node tree [ N << 2 ] ;
    void build ( int k , int l , int r ) {
        if ( l == r ) { tree [ k ] . init ( 0 , a [ l ] ) ; return ; }
        int mid = l + r >> 1 ;
        build ( k << 1 , l , mid );
        build ( k << 1 | 1 , mid + 1 , r );
        tree [ k ] . sum = min ( tree [ k << 1 ] . sum , tree [ k << 1 | 1 ] . sum ) ;
        return ;
    }
    void push_down ( int k ) {
        if ( tree [ k ] . tag == 0 ) return;

        tree [ k << 1 ] . tag += tree [ k ] . tag;
        tree [ k << 1 | 1 ]  . tag += tree [ k ] . tag;

        tree [ k << 1 ] . sum += tree [ k ] . tag;
        tree [ k << 1 | 1 ] . sum += tree [ k ] . tag;

        tree [ k ] . tag = 0 ;
        return ;
    }
    void update ( int k , int l , int r , int x , int y , int z ) {
        if ( l >= x && r <= y ) {
            tree [ k ] . tag += z;
            tree [ k ] . sum += z;
            return;
        }
        int mid = l + r >> 1 ;
        push_down ( k ) ;
        if ( x <= mid ) update ( k << 1 , l , mid , x , y , z ) ;
        if ( y > mid ) update ( k << 1 | 1 , mid + 1 , r , x , y , z ) ;
        tree [ k ] . sum = min ( tree [ k << 1 ] . sum , tree [ k << 1 | 1 ] . sum ) ;
        return ;
    }
    int query ( int k , int l , int r , int x , int y ) {
        if ( l >= x && r <= y ) { return tree [ k ] . sum ; }
        int mid = l + r >> 1 ;
        push_down ( k ) ;
        int rhs = ( 1 << 30 );
        if ( x <= mid ) rhs = min ( rhs , query ( k << 1 , l , mid , x , y ) ) ;
        if ( y > mid ) rhs = min ( rhs , query ( k << 1 | 1 , mid + 1 , r , x , y ) ) ;
        return rhs ;
    }
}
int main ( ) {
    // freopen ( "text.in" , "r" , stdin ) ;
    cin >> n >> m;
    for ( int i = 1 ; i <= n ; i ++ ) {
        cin >> a [ i ] ;
    }
    xds :: build ( 1 , 1 , n ) ;
    for ( int i = 1 ; i <= m ; i ++ ) {
        static int x , y , z  ;
        cin >> z >> x >> y ;
        if ( xds :: query ( 1 , 1 , n , x , y ) >= z ) xds :: update ( 1 , 1 , n , x , y , -z ) ;
        else {
            return printf ( "-1\n%d\n" , i ) * 0 ;
        }
    }
    puts("0");
    return 0 ;
}