Codeforces Round #169 (Div. 2) C. Little Girl and Maximum Sum 差分问题 - 服务器托管|北京服务器租用|机房托管租用|IDC托管租用|机房机柜带宽租用-价格及费用咨询

The little girl loves the problems on array queries very much.

One day she came across a rather well-known problem: you’ve got an array of n elements (the elements of the array are indexed starting from 1); also, there are q queries, each one is defined by a pair of integers li, ri (1 ≤ li ≤ ri ≤ n). You need to find for each query the sum of elements of the array with indexes from li to ri, inclusive.

The little girl found the problem rather boring. She decided to reorder the array elements before replying to the queries in a way that makes the sum of query replies maximum possible. Your task is to find the value of this maximum sum.

Input
The first line contains two space-separated integers n (1 ≤ n ≤ 2·105) and q (1 ≤ q ≤ 2·105) — the number of elements in the array and the number of queries, correspondingly.

The next line contains n space-separated integers ai (1 ≤ ai ≤ 2·105) — the array elements.

Each of the following q lines contains two space-separated integers li and ri (1 ≤ li ≤ ri ≤ n) — the i-th query.

Output
In a single line print a single integer — the maximum sum of query replies after the array elements are reordered.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Examples
inputCopy
3 3
5 3 2
1 2
2 3
1 3
outputCopy
25
inputCopy
5 3
5 2 4 1 3
1 5
2 3
2 3
outputCopy
33

貌似用差分维护一下即可，记录端点即可：

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
typedef long long ll;
using namespace std;
#define maxn 3000005
#define inf 0x3f3f3f3f
const long long int mod = 1e9 + 7;

ll read() {
    ll x = 0, f = 1;
    char ch = getchar();
    while (ch '9') {
        if (ch == '-') {
            f = -1;
        }
        ch = getchar();
    }
    while (ch >= '0'&&ch  0) {
        if (b % 2)ans = ans * a;
        b = b / 2;
        a = a * a;
    }
    return ans;
}

int gcd(int a, int b) {
    return b == 0 ? a : gcd(b, a%b);
}


bool cmp(int a, int b) {
    return a > b;
}

ll a[maxn];
ll sum[maxn];
ll dt[maxn];

int main() {
    ios::sync_with_stdio(false);
    int n,q;
    cin>>n>>q;
    int i,j;
    for(i=1;i>a[i];
    for(int i=1;i>l>>r;
        dt[r+1]--;
        dt[l]++;
    }
    for(i=1;i

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