洛谷P1941 飞扬的小鸟(背包 dp)
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2022-07-02 15:55:42
题意 "题目链接" Sol 很显然的dp,设$f[i][j]$表示第$i$个位置,高度为$j$的最小步数 向上转移的时候是完全背包 向下转移判断一下就可以 cpp include define Fin(x) {freopen(x, "r", stdin);} define chmin(a, b) ( ......
题意
sol
很显然的dp,设\(f[i][j]\)表示第\(i\)个位置,高度为\(j\)的最小步数
向上转移的时候是完全背包
向下转移判断一下就可以
#include<bits/stdc++.h> #define fin(x) {freopen(x, "r", stdin);} #define chmin(a, b) (a = (a < b ? a : b)) //#define int long long using namespace std; const int maxn = 10001, mod = 19997, inf = 1e9 + 10; inline int read() { char c = getchar(); int x = 0, f = 1; while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();} while(c >= '0' && c <= '9') x = (x * 10 + c - '0') % mod, c = getchar(); return x * f; } int n, m, k; int x[maxn], y[maxn], l[maxn], h[maxn], f[2][1001], mx, vis[maxn];//i:pos j:height signed main() { n = read(); m = read(); k = read(); l[0] = 1; h[0] = m; for(int i = 1; i <= n; i++) x[i - 1] = read(), y[i - 1] = read(), l[i] = 1, h[i] = m; for(int i = 1; i <= k; i++) { int p = read(); l[p] = read() + 1; h[p] = read() - 1; vis[p] = 1; } for(int i = 0; i <= m; i++) f[0][i] = 0; int o = 0; for(int i = 0, cnt = 0; i < n; i++, o ^= 1) { memset(f[o ^ 1], 0x3f, sizeof(f[o ^ 1])); if(vis[i]) cnt++; for(int j = 0; j <= m; j++) { int nxt = j + x[i] > m ? m : j + x[i]; chmin(f[o ^ 1][nxt], f[o][j] + 1); chmin(f[o ^ 1][nxt], f[o ^ 1][j] + 1); if(j - y[i] >= l[i + 1]) chmin(f[o ^ 1][j - y[i]], f[o][j]); } for(int j = 0; j < l[i + 1]; j++) f[o ^ 1][j] = inf; for(int j = h[i + 1] + 1; j <= m; j++) f[o ^ 1][j] = inf; for(int j = 0; j <= m; j++) if(f[o][j] < inf && vis[i]) mx = cnt; } int ans = inf; for(int i = l[n]; i <= h[n]; i++) ans = min(ans, f[o][i]); if(ans < inf) printf("1\n%d", ans); else printf("0\n%d", mx); return 0; }
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