[HDOJ5057] Argestes and Sequence (分块, 暴力)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5057

分块，维护每块中每位的每个数位出现的次数。

#include <bits/stdc++.h>
using namespace std;

const int maxn = 100100;
const int maxm = 1010;
int be[maxn], b[maxm][11][11];
int n, sz, q, a[maxn];
char cmd[5];

int mul(int x, int n) {
    int ret = 1;
    while(n) {
        if(n & 1) ret *= x;
        n >>= 1;
        x *= x;
    }
    return ret;
}

void update(int pos, int val) {
    if(a[pos] == val) return;
    for(int i = 1; i <= 10; i++) {
        b[be[pos]][i][a[pos]%10]--;
        a[pos] /= 10;
    }
    a[pos] = val;
    for(int i = 1; i <= 10; i++) {
        b[be[pos]][i][val%10]++;
        val /= 10;
    }
}

int query(int l, int r, int d, int p) {
    int ret = 0;
    for(int i = l; i <= r; ) {
        if(i + sz <= r && i % sz == 0) {
            ret += b[be[i]][d][p];
            i += sz;
        }
        else {
            ret += (a[i] / mul(10, d-1) % 10 == p);
            i++;
        }
    }
    return ret;
}

signed main() {
    // freopen("in", "r", stdin);
    int T, l, r, d, p;
    scanf("%d", &T);
    while(T--) {
        memset(b, 0, sizeof(b));
        scanf("%d%d",&n,&q);
        sz = (int)sqrt(n);
        for(int i = 0; i < n; i++) {
            scanf("%d", &a[i]);
            be[i] = i / sz;
            int val = a[i];
            for(int j = 1; j <= 10; j++) {
                b[be[i]][j][val%10]++;
                val /= 10;
            }
        }
        while(q--) {
            scanf("%s", cmd);
            if(cmd[0] == 'Q') {
                scanf("%d%d%d%d",&l,&r,&d,&p);
                printf("%d
", query(--l, --r, d, p));
            }
            else {
                scanf("%d%d",&d,&p);
                update(--d, p);
            }
        }
    }
    return 0;
}