【POJ】3468 A Simple Problem with Integers

线段树。段区间，终于完全自己A掉的。

#include <cstdio>
#include <cstring>

#define MAXN 100005
#define lson l, mid, rt<<1
#define rson mid+1, r, rt<<1|1

__int64 sums[MAXN<<2];
__int64 adds[MAXN<<2];

inline void PushUP(int rt) {
    sums[rt] = sums[rt<<1] + sums[rt<<1|1];
}

inline void PushDown(int len, int rt) {
    if ( adds[rt] ) {
        adds[rt<<1] += adds[rt];
        adds[rt<<1|1] += adds[rt];
        sums[rt<<1|1] += adds[rt] * (len>>1);
        sums[rt<<1] += adds[rt] * (len-(len>>1));
        adds[rt] = 0;
    }
}

void build(int l, int r, int rt) {
    int mid;
    adds[rt] = 0;
    if (l == r) {
        scanf("%I64d", &sums[rt]);
        return ;
    }
    mid = (l+r)>>1;
    build(lson);
    build(rson);
    PushUP(rt);
}

void update(int ll, int rr, int c, int l, int r, int rt) {
    int mid;
    if (ll<=l && rr>=r) {
        sums[rt] += c*(r-l+1);
        adds[rt] += c;
        return ;
    }
    PushDown(r-l+1, rt);
    mid = (l+r)>>1;
    if (ll <= mid)
        update(ll, rr, c, lson);
    if (rr > mid)
        update(ll, rr, c, rson);
    PushUP(rt);
}

__int64 query(int ll, int rr, int l, int r, int rt) {
    int mid;
    __int64 ret = 0;
    if (ll<=l && rr>=r)
        return sums[rt];
    PushDown(r-l+1, rt);
    mid = (l+r)>>1;
    if (ll <= mid)
        ret += query(ll, rr, lson);
    if (rr > mid)
        ret += query(ll, rr, rson);
    //PushUP(rt);
    return ret;
}

int main() {
    int n, m;
    int x, y, c;
    char cmd[3];

    while (scanf("%d %d", &n, &m) != EOF) {
        build(1, n, 1);

        while (m--) {
            scanf("%s %d %d", cmd, &x, &y);
            if (cmd[0] == 'C') {
                scanf("%d", &c);
                update(x,y,c,1,n,1);
            } else {
                printf("%I64d
", query(x,y,1,n,1));
            }
        }
    }

    return 0;
}