BestCoder Round #33

A和B做法和官方题解一样

C题我是用背包+map，先把任务按最早开始的时间进行排序，然后去背包，dp[j]表示j时间能得到最大的得分，然后就过了。。

代码：

A：

#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

int n, b;

char str[205];
int ans[205];

int get(char c) {
    if (c >= '0' && c <= '9') return c - '0';
    return c - 'a' + 10;
}

void print(int c) {
    if (c >= 0 && c <= 9) printf("%d", c);
    else printf("%c", c + 'a' - 10);
}

int main() {
    while (~scanf("%d%d", &n, &b)) {
        memset(ans, 0, sizeof(ans));
        while (n--) {
            scanf("%s", str);
            int len = strlen(str);
            for (int i = len - 1; i >= 0; i--) {
                ans[len - i - 1] += get(str[i]);
            }
        }
        for (int i = 0; i < 204; i++) {
            ans[i] %= b;
        }
        int i;
        for (i = 204; i >= 0; i--) {
            if (ans[i])
                break;
        }
        if (i == -1) i++;
        for (int j = i; j >= 0; j--)
            print(ans[j]);
        printf("\n");
    }
    return 0;
}

B：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

typedef long long ll;

ll n, p;

ll muti(ll a, ll n, ll p) {
    ll r = 0;
    while(n){
        if(n&1){
            r += a;
            if(r >= p) r -= p;
        }
        n >>= 1;
        a += a;
        if(a >= p) a -= p;
    }
    return r;
}

ll pow_mod(ll x, ll k) {
    ll ans = 1;
    x %= p;
    while (k) {
        if (k&1) ans = muti(ans, x, p);
        x = muti(x, x, p);
        k >>= 1;
    }
    return ans;
}

int main() {
    while (~scanf("%I64d%I64d", &n, &p)) {
        if (n == 1) printf("%I64d\n", n % p);
        else printf("%I64d\n", ((pow_mod(2LL, n) - 2) % p + p) % p);
    }
    return 0;
}

C：

#include <cstdio>
#include <cstring>
#include <map>
#include <algorithm>
using namespace std;

typedef long long ll;
const int N = 35;

int n;
ll w;

struct Q {
    int t, v, l, s;
    void read() {
        scanf("%d%d%d", &t, &v, &l);
        s = max(0, l - t);
    }
} q[N];

map<int, ll> dp[2];
map<int, ll>::iterator it;

bool cmp(Q a, Q b) {
    if (a.s == b.s) return a.t < b.t;
    return a.s < b.s;
}

int main() {
    while (~scanf("%d%I64d", &n, &w)) {
        ll sum = 0;
        for (int i = 0; i < n; i++) {
            q[i].read();
            sum += q[i].v;
        }
        if (sum < w) {
            printf("zhx is naive!\n");
            continue;
        }
        sort(q, q + n, cmp);
        int now = 0, pre = 1;
        dp[now].clear();
        dp[now][0] = 0;
        for (int i = 0; i < n; i++) {
            swap(now, pre);
            dp[now].clear();
            for (it = dp[pre].begin(); it != dp[pre].end(); it++) {
                int pt = it->first;
                ll pw = it->second;
                dp[now][pt] = max(dp[now][pt], pw);
                int ut = max(pt, q[i].s) + q[i].t;
                dp[now][ut] = max(dp[now][ut], pw + q[i].v);
            }
        }
        for (it = dp[now].begin(); it != dp[now].end(); it++) {
            if (it->second >= w) {
                int ans = it->first;
                printf("%d\n", ans);
                break;
            }
        }
    }
    return 0;
}