链表的增加与删除
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
const int N = 1e4 + 10;
int nxt[N], val[N];
int tot = 0;
void init(int n) {
int node;
for (int i = 0; i < n; i++) {
node = tot;
int v;
scanf("%d", &v);
val[tot] = v;
nxt[tot] = node+1;
tot++;
}
nxt[node] = -1;
}
bool myfind(int x) {
for (int i = 0; i != -1; i = nxt[i]) {
if (val[i] == x) {
return 1;
}
}
return 0;
}
bool add(int x, int y) {
if (myfind(x) == 0 || myfind(y) == 1) {
return 0;
}
for (int i = 0; i != -1; i = nxt[i]) {
// Never Gonna Give You Up
if (val[i] == x) {
int node = tot;
val[tot] = y;
nxt[node] = nxt[i];
nxt[i] = node;
tot++;
return 1;
}
}
return 0;
}
bool del(int x) {
for (int i = 0; i != -1; i = nxt[i]) {
if (val[nxt[i]] == x) {
nxt[i] = nxt[nxt[i]];
return 1;
}
}
return 0;
}
int main() {
int n, q;
cin >> n;
init(n);
cin >> q;
while (q--) {
int op;
scanf("%d", &op);
if (op == 1) {
int x, y;
scanf("%d%d", &x, &y);
if (add(x, y)) {
printf("success\n");
} else {
printf("failed\n");
}
} else {
int x;
scanf("%d", &x);
if (del(x)) {
printf("success\n");
} else {
printf("failed\n");
}
}
}
for (int i = 0; i != -1; i = nxt[i]) {
cout << val[i] << " ";
}
return 0;
}
递推式
#include <bits/stdc++.h>
using namespace std;
const int p = 1e9 + 7;
int a, b;
int mi(int a, int b) {
int ret = 1;
while (b != 0) {
if (b % 2 == 1) {
ret = 1LL * ret * a % p;
}
a = 1LL * a * a % p;
b >>= 1; // 除以 2
}
return ret;
}
int main() {
cin >> a >> b;
cout << mi(a, b) % p;
return 0;
}
二分
不重复
递归代码
#include <algorithm>
#include <cstdio>
#include <iostream>
using namespace std;
const int N = 1e5 + 999;
int n, a[N], k;
int findNum(int l, int r, int num) {
int ret = -1;
int mid = (l + r) / 2;
if (a[mid] == num) {
ret = mid;
return mid;
} else if (a[mid] < num) {
return findNum(mid + 1, r, num);
} else {
return findNum(l, mid - 1, num);
}
}
int main() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
cin >> k;
cout << findNum(0, n, k);
return 0;
}
递推
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 999;
int n, a[N], k;
int findNum(int num) {
int l = 1;
int r = n;
while (l <= r) {
int mid = (l + r) / 2; // 分
if (a[mid] == num) {
return mid;
} else if (a[mid] < num) {
l = mid + 1; // 右移
} else {
r = mid - 1; // 左移
}
}
return -1;
}
int main() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
cin >> k;
cout << findNum(k);
return 0;
}
左端点
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int n, a[N], k;
int findNum(int num) {
int l = 1;
int r = n;
int ret = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (a[mid] == num) {
ret = mid;
r = mid - 1; // 找到了再往左边找找
} else if (a[mid] < num) {
l = mid + 1;
} else {
r = mid - 1;
}
}
return ret;
}
int main() {
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
cout << findNum(k);
return 0;
}
右端点
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int n, a[N], k;
int findNum(int num) {
int l = 1;
int r = n;
int ret = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (a[mid] == num) {
ret = mid;
l = mid + 1; // 找到了再往右边找找
} else if (a[mid] < num) {
l = mid + 1;
} else {
r = mid - 1;
}
}
return ret;
}
int main() {
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
cout << findNum(k);
return 0;
}
其他
流加速(cin
cout
)
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
全排列
#include <bits/stdc++.h>
using namespace std;
int a[15], n, vis[15];
void dfs(int k) {
if (k > n) {
for (int i = 1; i <= n; i++) {
cout << a[i] << " ";
}
cout << endl;
return;
}
for (int i = 1; i <= n; i++) {
if (vis[i] != 1) {
vis[i] = 1;
a[k] = i;
dfs(k+1);
vis[i] = 0;
}
}
}
int main() {
cin >> n;
dfs(1);
return 0;
}