HihoCoder 1078 线段树区间更新

传送门：HihoCoder 1078

题解

就是一个lazy标记

code:

/*adrui's submissionLanguage : C++Result : AcceptedLove : llFavorite : Dragon BallsStanding in the Hall of Fame*/#include<cstdio>#include<cstring>#include<algorithm>#include<iostream>using namespace std;#define debug 0#define mid ((l + r) >> 1)#define ls rt << 1, l, mid#define rs rt << 1|1, mid + 1, r#define LL long long#define MOD 12357#define M(a, b) memset(a, b, sizeof(a))const int maxn(1e5 + 7);int n;struct {    int v;    int lazy;}node[maxn << 2];void pushUp(int rt) {    node[rt].v = node[rt << 1].v + node[rt << 1 | 1].v;}void pushDown(int rt, int m) {    if (node[rt].lazy != 0) {        //node[rt].v = m * node[rt].lazy;        node[rt << 1].v = node[rt].lazy * (m - (m >> 1));        node[rt << 1|1].v = node[rt].lazy * (m >> 1);        node[rt << 1].lazy = node[rt << 1 | 1].lazy = node[rt].lazy;        node[rt].lazy = 0;;    }}void build(int rt, int l, int r) {    if (l == r) {        scanf("%d", &node[rt].v);        return;    }    build(ls);    build(rs);    pushUp(rt);}void update(int rt, int l, int r, int ul, int ur, int cal) {    if (ul <= l && ur >= r) {        node[rt].lazy = cal;        node[rt].v = (r - l + 1) * cal;        return;    }    pushDown(rt, r - l + 1);    if (ul <= mid) {        update(ls, ul, ur, cal);    }    if (ur > mid) {        update(rs, ul, ur, cal);    }    pushUp(rt);}int query(int rt, int l, int r, int ql, int qr) {    if (ql <= l && qr >= r) {        return node[rt].v;    }    pushDown(rt, r - l + 1);    int res = 0;    if (ql <= mid)  res += query(ls, ql, qr);    if (qr > mid)   res += query(rs, ql, qr);    return res;}int main() {#if debug    freopen("in.txt", "r", stdin);#endif //debug    int q, k, a, b, c;    M(node, 0);    scanf("%d", &n);    build(1, 1, n);    scanf("%d", &q);    while (q--) {        scanf("%d", &k);        if (k) {            scanf("%d%d%d", &a, &b, &c);            update(1, 1, n, a, b, c);        }        else {            scanf("%d%d", &a, &b);            printf("%d\n", query(1, 1, n, a, b));        }    }    return 0;}