在省選前一天據說正式選手線畫到省二,有了別的女選手,慌的一批,而後刷了一個ARC來稍微找回一點代碼感受c++
最後仍是掛分了,不開心ide
果真水平退化老年加劇啊spa
原題連接code
直接作一個dp,找最大值時不找整十的位置便可rem
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 100005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int N; int s[105]; int dp[100005]; void Solve() { read(N); dp[0] = 1; for(int i = 1 ; i <= N ; ++i) { read(s[i]); for(int j = 100000 ; j >= 1 ; --j) { if(j >= s[i]) dp[j] = dp[j] | dp[j - s[i]]; } } for(int j = 100000 ; j >= 0 ; --j) { if(j && j % 10 == 0) continue; if(dp[j]) {out(j);enter;return;} } } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
二分操做次數,至關於每一個數集體減去\(mid * B\),而後分配\(mid\)個\(A - B\)給還未減到0的數get
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 100005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int N; int64 B,A; int64 h[MAXN]; void Solve() { read(N);read(A);read(B); for(int i = 1 ; i <= N ; ++i) { read(h[i]); } sort(h + 1,h + N + 1); int64 L = 0,R = 1000000000; while(L < R) { int64 mid = (L + R) >> 1; int64 rem = 0; for(int i = 1 ; i <= N ; ++i) { if(h[i] - mid * B > 0) rem += (h[i] - mid * B - 1) / (A - B) + 1; } if(rem <= mid) R = mid; else L = mid + 1; } out(L);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
每一個數都減去K,合法區間即爲和大於0的區間it
記成前綴和轉化成二維偏序的問題class
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 200005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int N,K,tr[MAXN]; int64 a[MAXN],sum[MAXN],val[MAXN]; int lowbit(int x) {return x & (-x);} void Insert(int x,int v) { while(x <= N + 1) { tr[x] += v; x += lowbit(x); } } int Query(int x) { int res = 0; while(x > 0) { res += tr[x]; x -= lowbit(x); } return res; } void Solve() { read(N);read(K); for(int i = 1 ; i <= N ; ++i) { read(a[i]); sum[i] = sum[i - 1] + a[i] - K; val[i] = sum[i]; } val[N + 1] = 0; sort(val + 1,val + N + 2); int t = lower_bound(val + 1,val + N + 2,sum[0]) - val; Insert(t,1); int64 res = 0; for(int i = 1 ; i <= N ; ++i) { t = lower_bound(val + 1,val + N + 2,sum[i]) - val; res += Query(t); Insert(t,1); } out(res);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }
若是長度固定爲L,每一個數位上的數是\(b_{i}\)那麼至關於test
\(rev(N) - N = \sum_{i = 0}^{L - 1} (10^{L - i - 1} - 10^{i})b_{i}\)bug
而後對稱的位置能夠合併一下
\(rev(N) - N = \sum_{i = 0}^{L / 2}(10^{L - i - 1} - 10^{i})(b_{i} - b_{L - i - 1})\)
而後咱們就至關於對於\(0-\lfloor \frac{L}{2}\rfloor\)中的每個\(10^{L - i - 1} - 10^{i}\)乘上一個\(-9\)到\(9\),組合出來的值是D,而後乘上這種方案的搭配數
而後發現對於一個
\(10^{L - i - 1} - 10^{i} > \sum_{j = i + 1}^{L / 2} (10^{L - j - 1} - 10^{j}) * 9\)
就是當前第i位決定完了,但和D差了大於\(10^{L - i - 1} - 10^{i}\)的時候,咱們是不管如何也恢復不了的
因此當D肯定時,合法的填法最多隻有兩個
對於固定的長度\(L\),最大是\(2L_{D}\)也就是D的十進制長度的二倍,最小是\(L_{D}\)
是二倍的緣由是D是正數,咱們若是要操做D必然要有在D大小之內的數加減,而後超過\(2L_{D}\)能加減的最小的數也超過了D,咱們沒法獲得一個D
#include <bits/stdc++.h> #define fi first #define se second #define pii pair<int,int> #define mp make_pair #define pb push_back #define space putchar(' ') #define enter putchar('\n') #define eps 1e-10 #define MAXN 200005 //#define ivorysi using namespace std; typedef long long int64; typedef unsigned int u32; typedef double db; template<class T> void read(T &res) { res = 0;T f = 1;char c = getchar(); while(c < '0' || c > '9') { if(c == '-') f = -1; c = getchar(); } while(c >= '0' && c <= '9') { res = res * 10 +c - '0'; c = getchar(); } res *= f; } template<class T> void out(T x) { if(x < 0) {x = -x;putchar('-');} if(x >= 10) { out(x / 10); } putchar('0' + x % 10); } int64 D; int Len(int64 D) { int res = 0; while(D) { res++; D /= 10; } return res; } int64 pw[20]; int64 v[20],d[20]; int up; int64 dfs(int64 rem,int dep) { if(dep == up) return !rem; int64 t = rem / v[dep]; int64 res = 0; if(abs(t - 1) <= 9 && abs(rem - (t - 1) * v[dep]) < v[dep]) { int c = 0; if(t - 1 >= 0 && !dep) c = 1; res += (d[t - 1 + 9] - c) * dfs(rem - (t - 1) * v[dep],dep + 1); } if(abs(t) <= 9 && abs(rem - t * v[dep]) < v[dep]) { int c = 0; if(t >= 0 && !dep) c = 1; res += (d[t + 9] - c) * dfs(rem - t * v[dep],dep + 1); } if(abs(t + 1) <= 9 && abs(rem - (t + 1) * v[dep]) < v[dep]) { int c = 0; if(t + 1 >= 0 && !dep) c = 1; res += (d[t + 1 + 9] - c) * dfs(rem - (t + 1) * v[dep],dep + 1); } return res; } void Solve() { read(D); int Ld = Len(D); int64 ans = 0; pw[0] = 1; for(int i = 1 ; i <= 18 ; ++i) pw[i] = pw[i - 1] * 10; for(int i = 0 ; i <= 9 ; ++i) { for(int j = 0 ; j <= 9 ; ++j) { d[i - j + 9]++; } } for(int i = Ld ; i <= 2 * Ld ; ++i) { for(int j = 0 ; j <= i / 2 ; ++j) v[j] = pw[i - j - 1] - pw[j]; up = i / 2; int64 tmp = dfs(D,0); if(i & 1) tmp *= d[0 + 9]; ans += tmp; } out(ans);enter; } int main() { #ifdef ivorysi freopen("f1.in","r",stdin); #endif Solve(); return 0; }