最大连续子序列和
题目类型:动态规划
#include<iostream>
#include<vector>
#include<algorithm>
#include<cstring>
using namespace std;
int n;
#define NMAX 1000006
int num[NMAX];
vector<long long > dp;
long long res;
int main() {
cin >> n;
memset(&res, 0xff, sizeof(res));
for (int i = 0; i < n; i++) cin >> num[i];
dp.push_back(num[0]);
for (int i = 1; i < n; i++) {
long long cur = max((long long)num[i], num[i] + dp[i - 1]);
dp.push_back(cur);
res = max(res, cur);
}
cout << res << endl;
}
二叉树形态总数
题目类型:动态规划
#include<iostream>
#include<vector>
#include<algorithm>
#include<cstring>
using namespace std;
int n;
#define NMAX 1003
long long dp[NMAX];
int main() {
cin >> n;
memset(dp, 0, sizeof(dp));
dp[1] = 1;
dp[0] = 1;
for (int i = 2; i <= n; i++) {
for (int j = 0; j <= i-1; j++) {
dp[i] += dp[j] * dp[i-1 - j];
}
}
cout << dp[n] << endl;
}
解方程
题目类型:模拟
#include<iostream>
#include<vector>
#include<algorithm>
#include<cstring>
using namespace std;
int n;
#define NMAX 1003
typedef long long LL;
LL var[2], val[2];
int pos;
char c;
int symbol = 1, num = 0, is = 0;
int main() {
memset(var, 0, sizeof(var));
memset(val, 0, sizeof(val));
pos = 0;
while ((c = getchar()) != '\n') {
if (c == 'x') {
is = 1;
if (num == 0) num = 1;//注意处理只有x时前面没有数字的情况
}
else if (c == '-' || c=='+' || c=='=') {
if (is) var[pos] += num * symbol;
else val[pos] += num * symbol;
if (c == '-') symbol = -1;
else symbol = 1;
num = 0;
is = 0;
if (c == '=') {
pos = 1;
}
}
else {
num = num * 10 + c - '0';
}
}
//最后的调试
if (is) var[pos] += num * symbol;
else val[pos] += num * symbol;
long long rvar = var[0] - var[1];
long long rval = val[1] - val[0];
if (rvar == rval && rvar == 0) cout << "infinite solutions" << endl;
else if (rvar == 0 && rvar != 0) cout << "no solution" << endl;
else cout << "x=" << rval / rvar << endl;
}