【HDOJ】3183 A Magic Lamp
RMQ。
1 /* 3183 */ 2 #include <cstdio> 3 #include <cstring> 4 #include <cstdlib> 5 6 #define MAXN 1005 7 8 char s[MAXN], ans[MAXN]; 9 int dp[MAXN][MAXN]; 10 int n,len,m; 11 12 int min(int x, int y) { 13 return s[x]<=s[y] ? x:y; 14 } 15 16 void RMQ_init() { 17 int i, j, k; 18 19 for (i=1; i<=len; ++i) 20 dp[i][0] = i; 21 for (j=1; (1<<j)<=len; ++j) 22 for (i=1; i+(1<<j)-1<=len; ++i) 23 dp[i][j] = min(dp[i][j-1], dp[i+(1<<(j-1))][j-1]); 24 } 25 26 int RMQ(int l, int r) { 27 int k = 0; 28 29 while ((1<<(k+1)) <= r-l+1) 30 ++k; 31 return min(dp[l][k], dp[r-(1<<k)+1][k]); 32 } 33 34 int main() { 35 int i, j, k; 36 int l; 37 38 #ifndef ONLINE_JUDGE 39 freopen("data.in", "r", stdin); 40 freopen("data.out", "w", stdout); 41 #endif 42 43 while (scanf("%s %d", s+1, &m)!=EOF) { 44 len = strlen(s+1); 45 RMQ_init(); 46 m = len - m; 47 l = k = 1; 48 while (m--) { 49 k = RMQ(k, len-m); 50 ans[l++] = s[k++]; 51 } 52 for (i=1; i<l; ++i) 53 if (ans[i] != '0') 54 break; 55 ans[l] = '\0'; 56 if (i == l) 57 puts("0"); 58 else 59 puts(ans+i); 60 } 61 62 return 0; 63 }
