HDU - 4669 Mutiples on a circle

5 7
9 6 4 2 8

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#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
typedef long long ll;
using namespace std;
const int maxn = 50010;
const int mod = 210;

int n, k;
int dp[maxn][305], num[maxn<<1];
int len[maxn<<1], doMod[maxn<<2];

int digit(int a) {
    int len = 0;
    while (a) {
        a /= 10;
        len++;
    }
    return len;
}

void getMod(int k, int n) {
    doMod[0] = 1;
    for (int i = 1; i <= n<<2; i++)
        doMod[i] = (doMod[i-1] * 10) % k;
}

int main() {
    int n, k;
    while (scanf("%d%d", &n, &k) != EOF) {
        for (int i = 1; i <= n; i++) {
            scanf("%d", &num[i]);
            num[i+n] = num[i];
        }

        getMod(k, n);
        for (int i = 0; i <= n; i++)
            for (int j = 0; j <= k; j++)
                dp[i][j] = 0;

        int r;
        for (int i = 1; i <= n; i++) {
            len[i+n] = len[i] = digit(num[i]);
            r = num[i] = num[i+n] = num[i] % k;
            dp[i][r]++;
        }

        r = num[1];
        int sunlen = 0;
        for (int i = n; i > 1; i--) {
            sunlen += len[i+1];
            r = (num[i] * doMod[sunlen] + r) % k;
            dp[1][r]++;
        }

        sunlen = 0;
        for (int i = 1; i <= n; i++)
            sunlen += len[i];

        int last = r;
        ll ans = dp[1][0];
        for (int i = 2; i <= n; i++) {
            for (int j = 0; j < k; j++) {
                r = (j * doMod[len[i]] + num[i]) % k;
                dp[i][r] += dp[i-1][j];
            }
            last = (last * doMod[len[i]] + num[i]) % k;
            dp[i][last]--;
            last = (last - (num[i] * doMod[sunlen]) % k + k) % k;
            ans += dp[i][0];
        }

        printf("%lld\n", ans);
    }
    return 0;
}

HDU - 4669 Mutiples on a circle

原文：http://blog.csdn.net/u011345136/article/details/41019127