42 lines
1.4 KiB
C++
42 lines
1.4 KiB
C++
#include <vector>
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#include <algorithm>
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#include <cstdio>
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/**
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* 1326. Minimum Number of Taps to Open to Water a Garden
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*
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* There is a one-dimensional garden on the x-axis. The garden starts at the point 0 and ends at the point n. (i.e The length of the garden is n).
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* There are n + 1 taps located at points [0, 1, ..., n] in the garden.
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* Given an integer n and an integer array ranges of length n + 1 where ranges[i] (0-indexed) means the i-th tap can water the area [i - ranges[i], i + ranges[i]] if it was open.
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* Return the minimum number of taps that should be open to water the whole garden, If the garden cannot be watered return -1.
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*/
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class Solution {
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public:
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static int minTaps(int n, const std::vector<int>& ranges) {
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std::vector<int> adv(n + 1, -1);
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for (int i = 0; i <= n; ++i) {
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if (!ranges[i])
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continue;
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// L, R inclusive
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int L = std::max(0, i - ranges[i]), R = std::min(n, i + ranges[i]);
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for (int j = L; j <= R; ++j)
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adv[j] = std::max(adv[j], R);
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}
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int ans = 0;
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for (int i = 0; i < n; ++ans) {
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if (adv[i] < i || (i == adv[i] && i < n))
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return -1;
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i = adv[i];
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}
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return ans;
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}
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};
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int main() {
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std::printf("%d\n", Solution::minTaps(35, {1,0,4,0,4,1,4,3,1,1,1,2,1,4,0,3,0,3,0,3,0,5,3,0,0,1,2,1,2,4,3,0,1,0,5,2}));
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std::printf("%d\n", Solution::minTaps(7, {1,2,1,0,2,1,0,1}));
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std::printf("%d\n", Solution::minTaps(3, {0,0,0,0}));
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std::printf("%d\n", Solution::minTaps(5, {3,0,1,1,0,0}));
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}
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