Codeforces Round #296 (Div. 2) A B C D

標籤：

A：類比輾轉相除法時記錄答案

B：3種情況：能減少2，能減少1，不能減少分別考慮清楚

C：利用一個set和一個multiset，把行列分開考慮，利用set內建的排序和查詢，每次把相應的塊拿出來分成兩塊插入回去，然後行列分別取最大相乘的作為這次詢問的答案

D：一個區間覆蓋問題的變形，注意公式的話，很容易發現其實x，w對應的就是一個[x - w, x + w]的區間，然後求最多不重合區間即可

代碼：

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;ll a, b, ans;ll gcd(ll a, ll b) {    if (!b) return a;    ans += a / b;    return gcd(b, a % b);}int main() {    scanf("%lld%lld", &a, &b);    gcd(a, b);    printf("%lld\n", ans);    return 0;}

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 200005;int n;char a[N], b[N];int g[30][30];int vis[30];int main() {    scanf("%d%s%s", &n, a + 1, b + 1);    int sum = 0;    for (int i = 1; i <= n; i++)        if (a[i] != b[i]) sum++;    for (int i = 1; i <= n; i++) {        if (a[i] != b[i]) {            if (g[b[i] - 'a'][a[i] - 'a']) {                printf("%d\n%d %d\n", sum - 2, i, g[b[i] - 'a'][a[i] - 'a']);                return 0;            }            g[a[i] - 'a'][b[i] - 'a'] = i;        }    }    for (int i = 1; i <= n; i++) {        if (a[i] != b[i]) {            vis[b[i] - 'a'] = i;        }    }    for (int i = 1; i <= n; i++) {        if (a[i] != b[i] && vis[a[i] - 'a']) {            printf("%d\n%d %d\n", sum - 1, i, vis[a[i] - 'a']);            return 0;        }    }    printf("%d\n-1 -1\n", sum);    return 0;}

#include <cstdio>#include <cstring>#include <algorithm>#include <set>using namespace std;int w, h, n;set<int> x[2];multiset<int> xx[2];char op[2];int v;set<int>::iterator it, l, r;multiset<int>::iterator tmp;long long gao(int tp) {    x[tp].insert(v);    it = x[tp].find(v);    l = it; l--; r = it; r++;    xx[tp].erase(xx[tp].find(*r - *l));    xx[tp].insert(v - *l);    xx[tp].insert(*r - v);    long long ans = 1;    tmp = xx[tp].end(); tmp--;    ans *= *tmp;    tmp = xx[!tp].end(); tmp--;    ans *= *tmp;    return ans;}int main() {    scanf("%d%d%d", &w, &h, &n);    x[0].insert(0); x[0].insert(w);    x[1].insert(0); x[1].insert(h);    xx[0].insert(w); xx[1].insert(h);    while (n--) {        scanf("%s%d", op, &v);        printf("%lld\n", gao(op[0] == 'H'));    }    return 0;}

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 200005;const int INF = 0x3f3f3f3f;struct Seg {    int l, r;    Seg() {}    Seg(int l, int r) {        this->l = l;        this->r = r;    }} seg[N];int n, x, w;bool cmp(Seg a, Seg b) {    return a.r < b.r;}int main() {    scanf("%d", &n);    for (int i = 0; i < n; i++) {        scanf("%d%d", &x, &w);        seg[i] = Seg(x - w, x + w);    }    sort(seg, seg + n, cmp);    int ans = 0;    int r = -INF;    for (int i = 0; i < n; i++) {        if (seg[i].l >= r) {            r = seg[i].r;            ans++;        }    }    printf("%d\n", ans);    return 0;}

Codeforces Round #296 (Div. 2) A B C D