本文主要是介绍Codeforces Educational Round 1 (ABCDE)，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
比赛链接：http://codeforces.com/contest/598
A. Tricky Sum
time limit per test：1 second
memory limit per test：256 megabytes
In this problem you are to calculate the sum of all integers from 1 to n, but you should take all powers of two with minus in the sum.
For example, for n = 4 the sum is equal to - 1 - 2 + 3 - 4 = - 4, because 1, 2 and 4 are 20, 21 and 22 respectively.
Calculate the answer for t values of n.
Input
The first line of the input contains a single integer t (1 ≤ t ≤ 100) — the number of values of n to be processed.
Each of next t lines contains a single integer n (1 ≤ n ≤ 109).
Output
Print the requested sum for each of t integers n given in the input.
Examples
input
2
4
1000000000
output
-4
499999998352516354
Note
The answer for the first sample is explained in the statement.
题目大意：求1到n的和，数字为2的次幂减，其余加
题目分析：分别求和然后减一下即可
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#define ll long long
using namespace std;int main() {int t;ll n;cin >> t;while (t--) {cin >> n;ll sum = (n & 1) ? (n + 1) / 2 * n : n / 2 * (n + 1);ll temp = 0;while (n) {n >>= 1;temp++;}temp--;ll sum2 = 2;while (temp) {sum2 <<= 1;temp--;}sum2 -= 1;cout << sum - (sum2 << 1) << endl;}
}
B. Queries on a String
time limit per test：2 seconds
memory limit per test：256 megabytes
You are given a string s and should process m queries. Each query is described by two 1-based indices li, ri and integer ki. It means that you should cyclically shift the substring s[li... ri] ki times. The queries should be processed one after another in the order they are given.
One operation of a cyclic shift (rotation) is equivalent to moving the last character to the position of the first character and shifting all other characters one position to the right.
For example, if the string s is abacaba and the query is l1 = 3, r1 = 6, k1 = 1 then the answer is abbacaa. If after that we would process the query l2 = 1, r2 = 4, k2 = 2 then we would get the string baabcaa.
Input
The first line of the input contains the string s (1 ≤ |s| ≤ 10 000) in its initial state, where |s| stands for the length of s. It contains only lowercase English letters.
Second line contains a single integer m (1 ≤ m ≤ 300) — the number of queries.
The i-th of the next m lines contains three integers li, ri and ki (1 ≤ li ≤ ri ≤ |s|, 1 ≤ ki ≤ 1 000 000) — the description of the i-th query.
Output
Print the resulting string s after processing all m queries.
Examples
input
abacaba
2
3 6 1
1 4 2
output
baabcaa
Note
The sample is described in problem statement.
题目大意：一个字符串，n个操作，每次将l到r位置旋转k个单位长度，求操作后的字符串
题目分析：串长很短，旋转操作具有周期性，因此k对子串长取模即可，旋转可以通过经典的三段逆序方式来实现
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int const MAX = 10005;
char s[MAX];void reverse(char* s, int l, int r) {while (l < r) {swap(s[l++], s[r--]);}
}int main() {scanf("%s", s);int m, l, r, k;scanf("%d", &m);while (m--) {scanf("%d %d %d", &l, &r, &k);l--;r--;k %= (r - l + 1);reverse(s, r - k + 1, r);reverse(s, l, r - k);reverse(s, l, r);}printf("%s\n", s);
}
C. Nearest vectors
time limit per test：2 seconds
memory limit per test：256 megabytes
You are given the set of vectors on the plane, each of them starting at the origin. Your task is to find a pair of vectors with the minimal non-oriented angle between them.
Non-oriented angle is non-negative value, minimal between clockwise and counterclockwise direction angles. Non-oriented angle is always between 0 and π. For example, opposite directions vectors have angle equals to π.
Input
First line of the input contains a single integer n (2 ≤ n ≤ 100 000) — the number of vectors.
The i-th of the following n lines contains two integers xi and yi (|x|, |y| ≤ 10 000, x2 + y2 > 0) — the coordinates of the i-th vector. Vectors are numbered from 1 to n in order of appearing in the input. It is guaranteed that no two vectors in the input share the same direction (but they still can have opposite directions).
Output
Print two integer numbers a and b (a ≠ b) — a pair of indices of vectors with the minimal non-oriented angle. You can print the numbers in any order. If there are many possible answers, print any.
Examples
input
4
-1 0
0 -1
1 0
1 1
output
3 4
input
6
-1 0
0 -1
1 0
1 1
-4 -5
-4 -6
output
6 5题目大意：平面上给n个向量（用点的坐标表示），求向量夹角最小的点的编号
题目分析：这个题除了精度毒瘤外就没什么了，极角排序后暴力即可
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
long double const PI = acos(-1.0);
int const MAX = 100005;
pair <long double, int> a[MAX];
int n, x, y;int main () {scanf("%d", &n);for (int i = 0; i < n; i++) {scanf("%d %d", &x, &y);a[i] = make_pair(atan2(y, x), i);}sort(a, a + n);long double mi = 10000.0, tmp;int ans1 = 0, ans2 = 0;for (int i = 0; i < n; i++) {tmp = a[(i + 1) % n].first - a[i].first;if (tmp < 0) {tmp += 2.0 * PI;}if (tmp < mi) {mi = tmp;ans1 = a[i].second + 1;ans2 = a[(i + 1) % n].second + 1;}}printf("%d %d\n", ans1, ans2);
}
D. Igor In the Museum
time limit per test：1 second
memory limit per test：256 megabytes
Igor is in the museum and he wants to see as many pictures as possible.
Museum can be represented as a rectangular field of n × m cells. Each cell is either empty or impassable. Empty cells are marked with '.', impassable cells are marked with '*'. Every two adjacent cells of different types (one empty and one impassable) are divided by a wall containing one picture.
At the beginning Igor is in some empty cell. At every moment he can move to any empty cell that share a side with the current one.
For several starting positions you should calculate the maximum number of pictures that Igor can see. Igor is able to see the picture only if he is in the cell adjacent to the wall with this picture. Igor have a lot of time, so he will examine every picture he can see.
Input
First line of the input contains three integers n, m and k (3 ≤ n, m ≤ 1000, 1 ≤ k ≤ min(n·m, 100 000)) — the museum dimensions and the number of starting positions to process.
Each of the next n lines contains m symbols '.', '*' — the description of the museum. It is guaranteed that all border cells are impassable, so Igor can't go out from the museum.
Each of the last k lines contains two integers x and y (1 ≤ x ≤ n, 1 ≤ y ≤ m) — the row and the column of one of Igor's starting positions respectively. Rows are numbered from top to bottom, columns — from left to right. It is guaranteed that all starting positions are empty cells.
Output
Print k integers — the maximum number of pictures, that Igor can see if he starts in corresponding position.
Examples
input
5 6 3
******
*..*.*
******
*....*
******
2 2
2 5
4 3
output
6
4
10
input
4 4 1
****
*..*
*.**
****
3 2
output
8题目大意：输入一个n*m的字符矩阵，k组询问，每组询问是一个点，求与该点所在的联通块直接相邻的'*'字符的数量
题目分析：DFS即可，DFS时对每个联通块标号
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
int const MAX = 1005;
int n, m, k;
char s[MAX][MAX];
bool vis[MAX][MAX];
int mp[MAX][MAX];
vector<int> ans;int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};int DFS(int id, int x, int y) {if (s[x][y] == '*') {return 1;}vis[x][y] = true;mp[x][y] = id;int num = 0;for (int i = 0; i < 4; i++) {int xx = x + dx[i];int yy = y + dy[i];if (!vis[xx][yy] && xx > 0 && yy > 0 && xx <= n && yy <= m) {num += DFS(id, xx, yy);}}return num;
}int main() {scanf("%d %d %d", &n, &m, &k);for (int i = 1; i <= n; i++) {scanf("%s", s[i] + 1);}int id = 0;for (int i = 1; i <= n; i++) {for (int j = 1; j <= m; j++) {if (s[i][j] == '.' && !vis[i][j]) {int res = DFS(id, i, j);ans.push_back(res);id++;}}}int x, y;while (k--) {scanf("%d %d", &x, &y);printf("%d\n", ans[mp[x][y]]);}
}
E. Chocolate Bar
time limit per test：2 seconds
memory limit per test：256 megabytes
You have a rectangular chocolate bar consisting of n × m single squares. You want to eat exactly k squares, so you may need to break the chocolate bar.
In one move you can break any single rectangular piece of chocolate in two rectangular pieces. You can break only by lines between squares: horizontally or vertically. The cost of breaking is equal to square of the break length.
For example, if you have a chocolate bar consisting of 2 × 3 unit squares then you can break it horizontally and get two 1 × 3 pieces (the cost of such breaking is 32 = 9), or you can break it vertically in two ways and get two pieces: 2 × 1 and 2 × 2 (the cost of such breaking is 22 = 4).
For several given values n, m and k find the minimum total cost of breaking. You can eat exactly k squares of chocolate if after all operations of breaking there is a set of rectangular pieces of chocolate with the total size equal to k squares. The remaining n·m - ksquares are not necessarily form a single rectangular piece.
Input
The first line of the input contains a single integer t (1 ≤ t ≤ 40910) — the number of values n, m and k to process.
Each of the next t lines contains three integers n, m and k (1 ≤ n, m ≤ 30, 1 ≤ k ≤ min(n·m, 50)) — the dimensions of the chocolate bar and the number of squares you want to eat respectively.
Output
For each n, m and k print the minimum total cost needed to break the chocolate bar, in order to make it possible to eat exactly ksquares.
Examples
input
4
2 2 1
2 2 3
2 2 2
2 2 4
output
5
5
4
0
Note
In the first query of the sample one needs to perform two breaks:
- to split 2 × 2 bar into two pieces of 2 × 1 (cost is 22 = 4),
- to split the resulting 2 × 1 into two 1 × 1 pieces (cost is 12 = 1).
In the second query of the sample one wants to eat 3 unit squares. One can use exactly the same strategy as in the first query of the sample.
题目大意：n*m的巧克力块，求在吃k块的情况下，最小切割代价，每次切割的代价为切割长度的平方
题目分析：数据范围很小，随便dp即可，dp[i][j][k]表示高为i，长为j的巧克力块吃k块的最小代价，暴力枚举横切和竖切的情况，以横切为例，假设在高为h的地方切一刀，会把巧克力分为h*j和(i-h)*j两块，假设当前枚举的切割后的上半部分的块数为up，下半部分则为k-up，易得转移方程dp[i][j][k] = min(dp[i][j][k], dp[h][j][up] + dp[i - h][j][k - up] + j * j，若i*j<=50，如果要吃大小为i*j的巧克力块的话是不需要额外切割的，比如样例的第四个，因此初始化时将i*j<=50的dp[i][j][i*j]设为0
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int const INF = 1e9;int dp[35][35][55];void pre() {for (int i = 0; i <= 30; i++) {for (int j = 0; j <= 30; j++) {for (int k = 0; k <= 50; k++) {dp[i][j][k] = INF;}}}for (int i = 0; i <= 30; i++) {for (int j = 0; j <= 30; j++) {dp[i][j][0] = 0;if (i * j <= 50) {dp[i][j][i * j] = 0;}}}for (int i = 1; i <= 30; i++) {for (int j = 1; j <= 30; j++) {for (int k = 1; k <= min(i * j, 50); k++) {for (int h = 1; h <= (i >> 1); h++) {for (int up = 0; up <= k; up++) {dp[i][j][k] = min(dp[i][j][k], dp[h][j][up] + dp[i - h][j][k - up] + j * j);}}for (int v = 1; v <= (j >> 1); v++) {for (int left = 0; left <= k; left++) {dp[i][j][k] = min(dp[i][j][k], dp[i][v][left] + dp[i][j - v][k - left] + i * i);}}}}}
}int main() {pre();int t, n, m, k;scanf("%d", &t);while (t--) {scanf("%d %d %d", &n, &m, &k);printf("%d\n", dp[n][m][k]);}
}
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