【NOIP提高A组模拟2018.8.14】 区间

区间加：差分数组修改

O(n)扫描，负数位置单调不减

#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>

using namespace std;

inline int rd(){
    int ret=,f=;char c;
    while(c=getchar(),!isdigit(c))f=c=='-'?-:;
    while(isdigit(c))ret=ret*+c-'',c=getchar();
    return ret*f;
}

const int MAXN=;

int a[MAXN],d[MAXN];
queue<int> Q1,Q2;
int n,ans;

int main(){
    freopen("range.in","r",stdin);
    freopen("range.out","w",stdout);
    n=rd();
    for(int i=;i<=n;i++) a[i]=rd();
    for(int i=;i<=n;i++){
        d[i]=a[i]-a[i-];
        if(d[i]>) ans+=d[i];
    }
    d[n+]=-(<<);
    printf("%d\n",ans);
    int j=;
    for(int i=;i<=n;i++){
        if(d[i]==) continue;
        while(d[i]!=){
            if(d[j]>=){j++;continue;}
            d[i]-=;
            d[j]+=;
            printf("%d %d\n",i,j-);
        }
    }
    return ;
}