codeforces.com/contest/897/

A

#include<stdio.h>int main(){    int n, m;    char s[102];    while(scanf("%d%d%s", &n, &m, s) != EOF) {        while(m--) {            int l, r;            char c1, c2;            scanf("%d%d %c %c", &l, &r, &c1, &c2);            for(int i = l; i <= r; ++i) {                if(s[i - 1] == c1) {                    s[i - 1] = c2;                }            }        }        puts(s);    }    return 0;}

B

#include<stdio.h>const int MAXN = (int)1e5 + 5;int k, p, cnt, t;typedef long long ll;int mod_pow(int a, int n) {    int res = 1;    while(n) {        if(n&1) res = 1LL * res * a % p;        a = 1LL * a * a % p;        n >>= 1;    }    return res;}int f(int j, int i) {    return 1LL * mod_pow(10, i) * j % p;}int dfs(int i, int sum, bool fg) {    if(cnt == k) return 0;    if(i == t / 2) {        ++cnt;        return sum;    }    int res = 0;    if(fg) res = dfs(i - 1, sum, true);    for(int j = 1; j <= 9; ++j) {        res += dfs(i - 1, ((sum + f(j, i - 1))%p + f(j, t - i)) % p, true);        res %= p;    }    return res;}int work() {    int res = 0;    cnt = 0;    for(int i = 2; cnt <= k; i += 2) {        res += dfs(t = i, 0, false);        res %= p;        if(cnt == k) break;    }    return res;}int main(){    while(scanf("%d%d", &k, &p) != EOF) {        int ans = work();        printf("%d\n", ans);    }    return 0;}

C

#include<stdio.h>#include<string.h>typedef long long ll;const char s0[] = "What are you doing at the end of the world? Are you busy? Will you save us?";const char s1[] = "What are you doing while sending \"";const char s2[] = "\"? Are you busy? Will you send \"";const char s3[] = "\"?";int l1, l2, l3, len, l0;void init() {    l0 = strlen(s0);    l1 = strlen(s1);    l2 = strlen(s2);    l3 = strlen(s3);    len = l1 + l2 + l3;}ll a(int k) {    if(k >= 55) return 5152117973711847356;    return (1LL<<k) * (len + l0) - len;}ll f(int i, int k) {    switch(i) {        case 0: return 0;        case 1: return l1;        case 2: return f(i - 1, k) + a(k - 1);        case 3: return f(i - 1, k) + l2;        case 4: return f(i - 1, k) + a(k - 1);        case 5: return f(i - 1, k) + l3;    }}char slove(int n, ll k) {    if(n == 0 && k <= l0) return s0[k - 1];    if(n == 0 && k > l0) return '.';    if(k <= f(1, n)) return s1[k - 1];    if(k <= f(2, n)) return slove(n - 1, k - f(1, n));    if(k <= f(3, n)) return s2[k - f(2, n) - 1];    if(k <= f(4, n)) return slove(n - 1, k - f(3, n));    if(k <= f(5, n)) return s3[k - f(4, n) - 1];    return '.';}int main(){    init();    /*    for(int i = 0; i <= 60; ++i) {        printf("# %d %lld\n", i, a(i));    }*/    int T;    while(scanf("%d", &T) != EOF) {        while(T--) {            int n;            ll k;            scanf("%d%lld", &n, &k);            printf("%c", slove(n, k));        }    }    return 0;}