P3396 哈希冲突

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#include<bits/stdc++.h>
using namespace std;
const int MAXn = 1e5 + 5e4;
const int MAXsqrtn = 387;

template <typename T>
inline void read(T &a) {
    char c;for (c = getchar(); (c < '0' || c > '9') && c != '-'; c = getchar());bool f = c == '-';T x = f ? 0 : (c ^ '0');for (c = getchar(); c >= '0' && c <= '9'; c = getchar()) {x = x * 10 + (c ^ '0');}a = f ? -x : x;
}
template <typename T, typename ...Argv>
inline void read(T &a, Argv &...argv) {
    read(a), read(argv...);
}

int n, sqrtn, m, a[MAXn + 10];
int small[MAXsqrtn + 10][MAXsqrtn + 10];
signed main() {
    read(n, m);
    sqrtn = sqrt(n);
    for (int i = 1; i <= n; ++i) {
        read(a[i]);
        for (int j = 1; j <= sqrtn; ++j) {
            small[j][i % j] += a[i];
        }
    }
    char opt;
    for (int i = 1; i <= m; ++i) {
        scanf("%s", &opt);
        if (opt == 'A') {
            int mod, yu;
            read(mod, yu);
            if (mod <= sqrtn) {
                printf("%d\n", small[mod][yu]);
            } else {
                int ans = 0;
                for (int i = (yu ? yu : mod); i <= n; i += mod) {
                    ans += a[i];
                }
                printf("%d\n", ans);
            }
        } else {
            int idx, val;
            read(idx, val);
            for (int i = 1; i <= sqrtn; ++i) {
                small[i][idx % i] += -a[idx] + val;
            }
            a[idx] = val;
        }
    }
    return 0;
}