60pts求调

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define MINLL -1e12;

const int MAXN = 1e6 + 7;

ll tree[4 * MAXN], mark_plus[4 * MAXN], num[MAXN], mark_exch[4 * MAXN];
ll n, m;
bool exchanged[4 * MAXN];

inline void read(ll& a) {
    ll s = 0, w = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-')
            w = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        s = s * 10 + ch - '0';
        ch = getchar();
    }
    a = s * w;
}

void build(ll l, ll r, ll p) {
    if (l == r) {
        tree[p] = num[l];
        return;
    }
    ll mid = (l + r) / 2;
    build(l, mid, p * 2);
    build(mid + 1, r, p * 2 + 1);
    tree[p] = max(tree[p * 2], tree[p * 2 + 1]);
}

void pushdown(ll p) {
    if (exchanged[p]) {
        mark_exch[p * 2] = mark_exch[p];
        mark_exch[p * 2 + 1] = mark_exch[p];
        tree[p * 2] = mark_exch[p];
        tree[p * 2 + 1] = mark_exch[p];
        exchanged[p * 2] = 1;
        exchanged[p * 2 + 1] = 1;
        exchanged[p] = 0;
    }
    mark_plus[p * 2] += mark_plus[p];
    mark_plus[p * 2 + 1] += mark_plus[p];
    tree[p * 2] += mark_plus[p];
    tree[p * 2 + 1] += mark_plus[p];;
    mark_plus[p] = 0;
    return;
}

void update(ll l, ll r, ll cl, ll cr, ll p, ll v) {
    if (r < cl || l > cr)return;
    if (cl >= l && cr <= r) {
        tree[p] += v;
        if (cr != cl)mark_plus[p] += v;
        return;
    }
    ll mid = (cl + cr) / 2;
    pushdown(p);
    update(l, r, cl, mid, p * 2, v);
    update(l, r, mid + 1, cr, p * 2 + 1, v);
    tree[p] = max(tree[p * 2], tree[p * 2 + 1]);
    return;

}

void clear(ll l, ll r, ll cl, ll cr, ll p, ll v) {

    if (r < cl || l > cr)return;
    if (cl >= l && cr <= r) {
        tree[p] = v;
        mark_plus[p] = 0;
        mark_exch[p] = v;
        exchanged[p] = 1;
        return;
    }
    ll mid = (cl + cr) / 2;
    pushdown(p);
    clear(l, r, cl, mid, p * 2, v);
    clear(l, r, mid + 1, cr, p * 2 + 1, v);
    tree[p] = max(tree[p * 2], tree[p * 2 + 1]);
    return;
}

ll get(ll l, ll r, ll cl, ll cr, ll p) {
    if (r < cl || l > cr)return MINLL;
    if (cl >= l && cr <= r) {
        return tree[p];
    }
    ll mid = (cl + cr) / 2;
    pushdown(p);;
    return max(get(l, r, cl, mid, p * 2), get(l, r, mid + 1, cr, p * 2 + 1));
}
int main() {
    freopen("P1253_7.in","r",stdin);
    freopen("P1253_7ma.out","w",stdout);
    cin >> n >> m;
    for (ll i = 1; i <= n; i++)read(num[i]);
    build(1, n, 1);
    for (ll i = 1; i <= m; i++) {
        ll op, l, r, x;
        read(op);
        read(l);
        read(r);
        switch (op) {
            case 1:
                read(x);
                clear(l, r, 1, n, 1, x);
                break;
            case 2:
                read(x);
                update(l, r, 1, n, 1, x);
                break;
            case 3:
                printf("%lld\n", get(l, r, 1, n, 1));
                break;
        }
    }
}
/*
6 6
1 1 4 5 1 4
1 1 2 6
2 3 4 2
3 1 4
3 2 3
1 1 6 -1
3 1 6

*/

后四个点WA，估计是标记在哪里打错了，查了一晚上都没查出来，更玄学的是如果每一步都get一次下一次的有一些点就对了，求大佬帮忙看看，非常感谢