Leetcode 1326. The minimum number of faucets to irrigate the garden (DAY 69) ---- Dynamic programming learning period (the algorithm problem path is so long and long, it does accumulate too little)

Original title

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Code implementation (most of the first brush to see the solution, a small part of self-solving)

class Solution {
    
    
public:
    int minTaps(int n, vector<int>& ranges) {
    
    
        vector<int> dp(n+1,INT_MAX);
        int l,r,pre;
        for(int i=0;i<=n;++i)
        {
    
    
            if(!ranges[i])  continue;
            l = max(0,i-ranges[i]);
            r = min(n,i+ranges[i]);

            pre = (l<=0 ? 0: dp[l]);
            if(pre == INT_MAX) continue;
            for(int temp = l;temp<=r;temp++)
                dp[temp] = min(dp[temp],pre+1);
        }
        return dp[n]==INT_MAX ? -1:dp[n];
    }
};