POJ - 3468 A Simple Problem with Integers （线段树区间更新---间接修改）

题意：区间add，区间求和。

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<deque>
#include<queue>
#include<list>
#define lowbit(x) (x & (-x))
const double eps = 1e-8;
inline int dcmp(double a, double b){
    if(fabs(a - b) < eps) return 0;
    return a > b ? 1 : -1;
}
typedef long long LL;
typedef unsigned long long ULL;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const LL LL_INF = 0x3f3f3f3f3f3f3f3f;
const LL LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const int dr[] = {0, 0, -1, 1, -1, -1, 1, 1};
const int dc[] = {-1, 1, 0, 0, -1, 1, -1, 1};
const int MOD = 1e9 + 7;
const double pi = acos(-1.0);
const int MAXN = 100000 + 10;
const int MAXT = 10000 + 10;
using namespace std;
LL a[MAXN];
LL sum[MAXN << 2];
LL lazy[MAXN << 2];
void build(int id, int L, int R){
    if(L == R){
        sum[id] = a[L];
    }
    else{
        int mid = L + (R - L) / 2;
        build(id << 1, L, mid);
        build(id << 1 | 1, mid + 1, R);
        sum[id] = sum[id << 1] + sum[id << 1 | 1];
    }
}
void pushdown(int id, int L, int R){
    if(lazy[id]){
        lazy[id << 1] += lazy[id];
        lazy[id << 1 | 1] += lazy[id];
        int mid = L + (R - L) / 2;
        sum[id << 1] += (mid - L + 1) * lazy[id];
        sum[id << 1 | 1] += (R - mid) * lazy[id];
        lazy[id] = 0;
    }
}
void update(int l, int r, int id, int L, int R, LL v){
    if(l <= L && R <= r){
        lazy[id] += v;
        sum[id] += (R - L + 1) * v;
    }
    else{
        pushdown(id, L, R);
        int mid = L + (R - L) / 2;
        if(l <= mid) update(l, r, id << 1, L, mid, v);
        if(r > mid) update(l, r, id << 1 | 1, mid + 1, R, v);
        sum[id] = sum[id << 1] + sum[id << 1 | 1];
    }
}
LL query(int l, int r, int id, int L, int R){
    if(l <= L && R <= r){
        return sum[id];
    }
    pushdown(id, L, R);
    int mid = L + (R - L) / 2;
    LL ans = 0;
    if(l <= mid) ans += query(l, r, id << 1, L, mid);
    if(r > mid) ans += query(l, r, id << 1 | 1, mid + 1, R);
    return ans;
}
int main(){
    int N, Q;
    scanf("%d%d", &N, &Q);
    for(int i = 1; i <= N; ++i){
        scanf("%lld", &a[i]);
    }
    build(1, 1, N);
    while(Q--){
        char cc;
        int a, b;
        getchar();
        scanf("%c%d%d", &cc, &a, &b);
        if(cc == 'C'){
            int c;
            scanf("%d", &c);
            update(a, b, 1, 1, N, (LL)c);
        }
        else{
            printf("%lld\n", query(a, b, 1, 1, N));
        }
    }
    return 0;
}