제출 #593091

#제출 시각아이디문제언어결과실행 시간메모리
593091Jomnoi밀림 점프 (APIO21_jumps)C++17
0 / 100
250 ms51244 KiB
#include <bits/stdc++.h> #include "jumps.h" using namespace std; const int MAX_N = 2e5 + 5; const int INF = 1e9 + 7; int N; int H[MAX_N]; int L[MAX_N], R[MAX_N], nxt[2][MAX_N][20]; int table[MAX_N][20]; void init(int n, vector <int> h) { N = n; for(int i = 1; i <= N; i++) { H[i] = h[i - 1]; table[i][0] = H[i]; } for(int j = 1; j < 20; j++) { for(int i = 1; i + (1<<j) - 1 <= N; i++) { table[i][j] = max(table[i][j - 1], table[i + (1<<(j - 1))][j - 1]); } } stack <int> stk; for(int i = 1; i <= N; i++) { while(!stk.empty() and H[stk.top()] < H[i]) { stk.pop(); } if(!stk.empty()) { L[i] = stk.top(); } stk.push(i); } while(!stk.empty()) { stk.pop(); } for(int i = N; i >= 1; i--) { while(!stk.empty() and H[stk.top()] < H[i]) { stk.pop(); } if(!stk.empty()) { R[i] = stk.top(); } stk.push(i); } for(int i = 1; i <= N; i++) { nxt[0][H[i]][0] = H[R[i]]; nxt[1][H[i]][0] = max(H[L[i]], H[R[i]]); for(int j = 1; j < 20; j++) { nxt[0][H[i]][j] = nxt[0][nxt[0][H[i]][j - 1]][j - 1]; nxt[1][H[i]][j] = nxt[1][nxt[1][H[i]][j - 1]][j - 1]; } } } int get_max(int l, int r) { if(l > r) { return -1; } int j = log2(r - l + 1); return max(table[l][j], table[r - (1<<j) + 1][j]); } int minimum_jumps(int A, int B, int C, int D) { A++, B++, C++, D++; int maxLeft = get_max(A, B); int maxMid = get_max(B + 1, C - 1); int maxRight = get_max(C, D); if(max(maxLeft, maxMid) > maxRight) { return -1; } int ans = 0; int l = A, r = B, now; while(l <= r) { int mid = (l + r) / 2; int mx = get_max(mid, B); if(mx < maxRight) { now = mx; r = mid - 1; } else { l = mid + 1; } } for(int i = 19; i >= 0; i--) { if(nxt[1][now][i] != 0 and nxt[1][now][i] < maxRight) { now = nxt[1][now][i]; ans += (1<<i); } } for(int i = 19; i >= 0; i--) { if(nxt[0][now][i] != 0 and nxt[0][now][i] < maxRight) { now = nxt[0][now][i]; ans += (1<<i); } } return ans + 1; }

컴파일 시 표준 에러 (stderr) 메시지

jumps.cpp: In function 'int minimum_jumps(int, int, int, int)':
jumps.cpp:97:25: warning: 'now' may be used uninitialized in this function [-Wmaybe-uninitialized]
   97 |         if(nxt[1][now][i] != 0 and nxt[1][now][i] < maxRight) {
      |            ~~~~~~~~~~~~~^
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